draw2d/image.go

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