Copied font functions from draw2dimg to draw2dgl
cursor -> width for certain functions for clarity Some panics added, some TODOs added
This commit is contained in:
redstarcoder
parent
13548be874
commit
105a963210
151
draw2dgl/gc.go
151
draw2dgl/gc.go
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@ -1,16 +1,23 @@
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package draw2dgl
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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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"runtime"
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"github.com/go-gl/gl/v2.1/gl"
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"github.com/golang/freetype/raster"
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"github.com/golang/freetype/truetype"
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"github.com/llgcode/draw2d"
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"github.com/llgcode/draw2d/draw2dbase"
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"github.com/llgcode/draw2d/draw2dimg"
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"golang.org/x/image/font"
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"golang.org/x/image/math/fixed"
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)
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func init() {
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@ -118,6 +125,8 @@ type GraphicContext struct {
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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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@ -127,54 +136,170 @@ func NewGraphicContext(width, height int) *GraphicContext {
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NewPainter(),
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raster.NewRasterizer(width, height),
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raster.NewRasterizer(width, height),
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&truetype.GlyphBuf{},
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92,
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}
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return gc
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}
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//FIXME copied from ../draw2dimg
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func (gc *GraphicContext) loadCurrentFont() (*truetype.Font, error) {
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font := draw2d.GetFont(gc.Current.FontData)
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if font == nil {
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font = draw2d.GetFont(draw2dbase.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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//FIXME copied from ../draw2dimg
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func (gc *GraphicContext) drawGlyph(glyph truetype.Index, dx, dy float64) error {
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if err := gc.glyphBuf.Load(gc.Current.Font, fixed.Int26_6(gc.Current.Scale), glyph, font.HintingNone); 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.Ends {
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DrawContour(gc, gc.glyphBuf.Points[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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//FIXME copied from ../draw2dimg
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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 *GraphicContext) CreateStringPath(s string, x, y float64) float64 {
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panic("not implemented")
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f, 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 := f.Index(rune)
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if hasPrev {
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x += fUnitsToFloat64(f.Kern(fixed.Int26_6(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(f.HMetric(fixed.Int26_6(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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func (gc *GraphicContext) FillStringAt(text string, x, y float64) (cursor float64) {
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panic("not implemented")
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func (gc *GraphicContext) FillStringAt(text string, x, y float64) (width 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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//FIXME copied from ../draw2dimg
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// GetStringBounds returns the approximate pixel bounds of the string s at x, y.
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// The 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 *GraphicContext) GetStringBounds(s string) (left, top, right, bottom float64) {
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panic("not implemented")
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f, 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 := f.Index(rune)
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if hasPrev {
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cursor += fUnitsToFloat64(f.Kern(fixed.Int26_6(gc.Current.Scale), prev, index))
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}
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if err := gc.glyphBuf.Load(gc.Current.Font, fixed.Int26_6(gc.Current.Scale), index, font.HintingNone); 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.Ends {
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ps := gc.glyphBuf.Points[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(f.HMetric(fixed.Int26_6(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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func (gc *GraphicContext) StrokeString(text string) (cursor float64) {
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func (gc *GraphicContext) StrokeString(text string) (width float64) {
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return gc.StrokeStringAt(text, 0, 0)
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}
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func (gc *GraphicContext) StrokeStringAt(text string, x, y float64) (cursor float64) {
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width := gc.CreateStringPath(text, x, y)
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func (gc *GraphicContext) StrokeStringAt(text string, x, y float64) (width 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 *GraphicContext) SetDPI(dpi int) {
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//FIXME copied from ../draw2dimg
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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 *GraphicContext) 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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func (gc *GraphicContext) 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 *GraphicContext) 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 *GraphicContext) 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 *GraphicContext) GetDPI() int {
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return -1
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return gc.DPI
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}
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//TODO
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func (gc *GraphicContext) Clear() {
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panic("not implemented")
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}
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//TODO
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func (gc *GraphicContext) ClearRect(x1, y1, x2, y2 int) {
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panic("not implemented")
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}
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//TODO
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func (gc *GraphicContext) DrawImage(img image.Image) {
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panic("not implemented")
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}
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func (gc *GraphicContext) FillString(text string) (cursor float64) {
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return 0
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return gc.FillStringAt(text, 0, 0)
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}
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func (gc *GraphicContext) paint(rasterizer *raster.Rasterizer, color color.Color) {
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@ -0,0 +1,83 @@
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package draw2dgl
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//Copied from ../draw2dimg
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import (
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"github.com/golang/freetype/truetype"
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"github.com/llgcode/draw2d"
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"golang.org/x/image/math/fixed"
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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 DrawContour(path draw2d.PathBuilder, 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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path.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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path.LineTo(qX+dx, qY+dy)
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} else {
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path.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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path.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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path.LineTo(startX+dx, startY+dy)
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} else {
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path.QuadCurveTo(q0X+dx, q0Y+dy, startX+dx, startY+dy)
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}
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}
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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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func fUnitsToFloat64(x fixed.Int26_6) 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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// FontExtents contains font metric information.
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type FontExtents struct {
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// Ascent is the distance that the text
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// extends above the baseline.
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Ascent float64
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// Descent is the distance that the text
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// extends below the baseline. The descent
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// is given as a negative value.
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Descent float64
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// Height is the distance from the lowest
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// descending point to the highest ascending
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// point.
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Height float64
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}
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// Extents returns the FontExtents for a font.
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// TODO needs to read this https://developer.apple.com/fonts/TrueType-Reference-Manual/RM02/Chap2.html#intro
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func Extents(font *truetype.Font, size float64) FontExtents {
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bounds := font.Bounds(fixed.Int26_6(font.FUnitsPerEm()))
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scale := size / float64(font.FUnitsPerEm())
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return FontExtents{
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Ascent: float64(bounds.Max.Y) * scale,
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Descent: float64(bounds.Min.Y) * scale,
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Height: float64(bounds.Max.Y-bounds.Min.Y) * scale,
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}
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}
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