359 lines
10 KiB
Go
359 lines
10 KiB
Go
// Copyright 2010 The draw2d Authors. All rights reserved.
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// created: 21/11/2010 by Laurent Le Goff
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package draw2d
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import (
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"errors"
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"image"
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"image/color"
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"image/draw"
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"log"
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"math"
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"code.google.com/p/freetype-go/freetype/raster"
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"code.google.com/p/freetype-go/freetype/truetype"
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)
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type Painter interface {
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raster.Painter
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SetColor(color color.Color)
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}
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var (
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defaultFontData = FontData{"luxi", FontFamilySans, FontStyleNormal}
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)
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type ImageGraphicContext struct {
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*StackGraphicContext
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img draw.Image
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painter Painter
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fillRasterizer *raster.Rasterizer
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strokeRasterizer *raster.Rasterizer
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glyphBuf *truetype.GlyphBuf
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DPI int
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}
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// NewGraphicContext creates a new Graphic context from an image.
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func NewGraphicContext(img draw.Image) *ImageGraphicContext {
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var painter Painter
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switch selectImage := img.(type) {
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case *image.RGBA:
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painter = raster.NewRGBAPainter(selectImage)
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default:
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panic("Image type not supported")
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}
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return NewGraphicContextWithPainter(img, painter)
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}
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// NewGraphicContextWithPainter creates a new Graphic context from an image and a Painter (see Freetype-go)
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func NewGraphicContextWithPainter(img draw.Image, painter Painter) *ImageGraphicContext {
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width, height := img.Bounds().Dx(), img.Bounds().Dy()
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dpi := 92
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gc := &ImageGraphicContext{
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NewStackGraphicContext(),
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img,
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painter,
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raster.NewRasterizer(width, height),
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raster.NewRasterizer(width, height),
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truetype.NewGlyphBuf(),
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dpi,
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}
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return gc
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}
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func (gc *ImageGraphicContext) GetDPI() int {
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return gc.DPI
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}
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func (gc *ImageGraphicContext) Clear() {
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width, height := gc.img.Bounds().Dx(), gc.img.Bounds().Dy()
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gc.ClearRect(0, 0, width, height)
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}
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func (gc *ImageGraphicContext) ClearRect(x1, y1, x2, y2 int) {
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imageColor := image.NewUniform(gc.Current.FillColor)
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draw.Draw(gc.img, image.Rect(x1, y1, x2, y2), imageColor, image.ZP, draw.Over)
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}
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func (gc *ImageGraphicContext) DrawImage(img image.Image) {
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DrawImage(img, gc.img, gc.Current.Tr, draw.Over, BilinearFilter)
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}
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func (gc *ImageGraphicContext) FillString(text string) (cursor float64) {
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return gc.FillStringAt(text, 0, 0)
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}
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func (gc *ImageGraphicContext) FillStringAt(text string, x, y float64) (cursor float64) {
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width := gc.CreateStringPath(text, x, y)
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gc.Fill()
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return width
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}
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func (gc *ImageGraphicContext) StrokeString(text string) (cursor float64) {
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return gc.StrokeStringAt(text, 0, 0)
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}
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func (gc *ImageGraphicContext) StrokeStringAt(text string, x, y float64) (cursor float64) {
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width := gc.CreateStringPath(text, x, y)
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gc.Stroke()
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return width
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}
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func (gc *ImageGraphicContext) loadCurrentFont() (*truetype.Font, error) {
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font := GetFont(gc.Current.FontData)
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if font == nil {
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font = GetFont(defaultFontData)
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}
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if font == nil {
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return nil, errors.New("No font set, and no default font available.")
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}
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gc.SetFont(font)
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gc.SetFontSize(gc.Current.FontSize)
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return font, nil
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}
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func fUnitsToFloat64(x int32) float64 {
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scaled := x << 2
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return float64(scaled/256) + float64(scaled%256)/256.0
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}
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// p is a truetype.Point measured in FUnits and positive Y going upwards.
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// The returned value is the same thing measured in floating point and positive Y
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// going downwards.
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func pointToF64Point(p truetype.Point) (x, y float64) {
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return fUnitsToFloat64(p.X), -fUnitsToFloat64(p.Y)
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}
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// drawContour draws the given closed contour at the given sub-pixel offset.
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func (gc *ImageGraphicContext) drawContour(ps []truetype.Point, dx, dy float64) {
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if len(ps) == 0 {
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return
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}
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startX, startY := pointToF64Point(ps[0])
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gc.MoveTo(startX+dx, startY+dy)
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q0X, q0Y, on0 := startX, startY, true
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for _, p := range ps[1:] {
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qX, qY := pointToF64Point(p)
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on := p.Flags&0x01 != 0
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if on {
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if on0 {
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gc.LineTo(qX+dx, qY+dy)
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} else {
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gc.QuadCurveTo(q0X+dx, q0Y+dy, qX+dx, qY+dy)
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}
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} else {
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if on0 {
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// No-op.
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} else {
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midX := (q0X + qX) / 2
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midY := (q0Y + qY) / 2
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gc.QuadCurveTo(q0X+dx, q0Y+dy, midX+dx, midY+dy)
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}
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}
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q0X, q0Y, on0 = qX, qY, on
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}
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// Close the curve.
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if on0 {
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gc.LineTo(startX+dx, startY+dy)
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} else {
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gc.QuadCurveTo(q0X+dx, q0Y+dy, startX+dx, startY+dy)
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}
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}
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func (gc *ImageGraphicContext) drawGlyph(glyph truetype.Index, dx, dy float64) error {
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if err := gc.glyphBuf.Load(gc.Current.Font, int32(gc.Current.Scale), glyph, truetype.NoHinting); err != nil {
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return err
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}
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e0 := 0
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for _, e1 := range gc.glyphBuf.End {
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gc.drawContour(gc.glyphBuf.Point[e0:e1], dx, dy)
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e0 = e1
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}
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return nil
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}
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// CreateStringPath creates a path from the string s at x, y, and returns the string width.
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// The text is placed so that the left edge of the em square of the first character of s
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// and the baseline intersect at x, y. The majority of the affected pixels will be
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// above and to the right of the point, but some may be below or to the left.
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// For example, drawing a string that starts with a 'J' in an italic font may
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// affect pixels below and left of the point.
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func (gc *ImageGraphicContext) CreateStringPath(s string, x, y float64) float64 {
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font, err := gc.loadCurrentFont()
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if err != nil {
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log.Println(err)
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return 0.0
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}
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startx := x
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prev, hasPrev := truetype.Index(0), false
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for _, rune := range s {
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index := font.Index(rune)
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if hasPrev {
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x += fUnitsToFloat64(font.Kerning(int32(gc.Current.Scale), prev, index))
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}
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err := gc.drawGlyph(index, x, y)
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if err != nil {
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log.Println(err)
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return startx - x
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}
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x += fUnitsToFloat64(font.HMetric(int32(gc.Current.Scale), index).AdvanceWidth)
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prev, hasPrev = index, true
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}
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return x - startx
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}
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// GetStringBounds returns the approximate pixel bounds of the string s at x, y.
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// The left edge of the em square of the first character of s
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// and the baseline intersect at 0, 0 in the returned coordinates.
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// Therefore the top and left coordinates may well be negative.
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func (gc *ImageGraphicContext) GetStringBounds(s string) (left, top, right, bottom float64) {
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font, err := gc.loadCurrentFont()
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if err != nil {
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log.Println(err)
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return 0, 0, 0, 0
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}
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top, left, bottom, right = 10e6, 10e6, -10e6, -10e6
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cursor := 0.0
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prev, hasPrev := truetype.Index(0), false
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for _, rune := range s {
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index := font.Index(rune)
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if hasPrev {
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cursor += fUnitsToFloat64(font.Kerning(int32(gc.Current.Scale), prev, index))
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}
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if err := gc.glyphBuf.Load(gc.Current.Font, int32(gc.Current.Scale), index, truetype.NoHinting); err != nil {
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log.Println(err)
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return 0, 0, 0, 0
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}
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e0 := 0
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for _, e1 := range gc.glyphBuf.End {
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ps := gc.glyphBuf.Point[e0:e1]
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for _, p := range ps {
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x, y := pointToF64Point(p)
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top = math.Min(top, y)
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bottom = math.Max(bottom, y)
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left = math.Min(left, x+cursor)
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right = math.Max(right, x+cursor)
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}
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}
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cursor += fUnitsToFloat64(font.HMetric(int32(gc.Current.Scale), index).AdvanceWidth)
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prev, hasPrev = index, true
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}
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return left, top, right, bottom
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}
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// recalc recalculates scale and bounds values from the font size, screen
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// resolution and font metrics, and invalidates the glyph cache.
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func (gc *ImageGraphicContext) recalc() {
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gc.Current.Scale = gc.Current.FontSize * float64(gc.DPI) * (64.0 / 72.0)
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}
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// SetDPI sets the screen resolution in dots per inch.
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func (gc *ImageGraphicContext) SetDPI(dpi int) {
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gc.DPI = dpi
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gc.recalc()
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}
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// SetFont sets the font used to draw text.
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func (gc *ImageGraphicContext) SetFont(font *truetype.Font) {
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gc.Current.Font = font
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}
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// SetFontSize sets the font size in points (as in ``a 12 point font'').
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func (gc *ImageGraphicContext) SetFontSize(fontSize float64) {
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gc.Current.FontSize = fontSize
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gc.recalc()
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}
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func (gc *ImageGraphicContext) paint(rasterizer *raster.Rasterizer, color color.Color) {
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gc.painter.SetColor(color)
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rasterizer.Rasterize(gc.painter)
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rasterizer.Clear()
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gc.Current.Path = NewPathStorage()
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}
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// Stroke strokes the paths with the color specified by SetStrokeColor
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func (gc *ImageGraphicContext) Stroke(paths ...*PathStorage) {
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paths = append(paths, gc.Current.Path)
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gc.strokeRasterizer.UseNonZeroWinding = true
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stroker := NewLineStroker(gc.Current.Cap, gc.Current.Join, NewVertexMatrixTransform(gc.Current.Tr, NewVertexAdder(gc.strokeRasterizer)))
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stroker.HalfLineWidth = gc.Current.LineWidth / 2
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var pathConverter *PathConverter
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if gc.Current.Dash != nil && len(gc.Current.Dash) > 0 {
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dasher := NewDashConverter(gc.Current.Dash, gc.Current.DashOffset, stroker)
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pathConverter = NewPathConverter(dasher)
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} else {
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pathConverter = NewPathConverter(stroker)
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}
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pathConverter.ApproximationScale = gc.Current.Tr.GetScale()
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pathConverter.Convert(paths...)
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gc.paint(gc.strokeRasterizer, gc.Current.StrokeColor)
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}
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// Fill fills the paths with the color specified by SetFillColor
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func (gc *ImageGraphicContext) Fill(paths ...*PathStorage) {
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paths = append(paths, gc.Current.Path)
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gc.fillRasterizer.UseNonZeroWinding = gc.Current.FillRule.UseNonZeroWinding()
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/**** first method ****/
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pathConverter := NewPathConverter(NewVertexMatrixTransform(gc.Current.Tr, NewVertexAdder(gc.fillRasterizer)))
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pathConverter.ApproximationScale = gc.Current.Tr.GetScale()
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pathConverter.Convert(paths...)
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gc.paint(gc.fillRasterizer, gc.Current.FillColor)
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}
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// FillStroke first fills the paths and than strokes them
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func (gc *ImageGraphicContext) FillStroke(paths ...*PathStorage) {
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gc.fillRasterizer.UseNonZeroWinding = gc.Current.FillRule.UseNonZeroWinding()
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gc.strokeRasterizer.UseNonZeroWinding = true
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filler := NewVertexMatrixTransform(gc.Current.Tr, NewVertexAdder(gc.fillRasterizer))
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stroker := NewLineStroker(gc.Current.Cap, gc.Current.Join, NewVertexMatrixTransform(gc.Current.Tr, NewVertexAdder(gc.strokeRasterizer)))
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stroker.HalfLineWidth = gc.Current.LineWidth / 2
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demux := NewDemuxConverter(filler, stroker)
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paths = append(paths, gc.Current.Path)
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pathConverter := NewPathConverter(demux)
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pathConverter.ApproximationScale = gc.Current.Tr.GetScale()
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pathConverter.Convert(paths...)
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gc.paint(gc.fillRasterizer, gc.Current.FillColor)
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gc.paint(gc.strokeRasterizer, gc.Current.StrokeColor)
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}
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func (f FillRule) UseNonZeroWinding() bool {
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switch f {
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case FillRuleEvenOdd:
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return false
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case FillRuleWinding:
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return true
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}
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return false
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}
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func (c Cap) Convert() raster.Capper {
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switch c {
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case RoundCap:
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return raster.RoundCapper
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case ButtCap:
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return raster.ButtCapper
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case SquareCap:
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return raster.SquareCapper
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}
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return raster.RoundCapper
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}
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func (j Join) Convert() raster.Joiner {
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switch j {
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case RoundJoin:
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return raster.RoundJoiner
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case BevelJoin:
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return raster.BevelJoiner
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}
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return raster.RoundJoiner
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}
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