need to be very specific about points vs. pixels.

This commit is contained in:
Will Charczuk 2016-07-09 09:04:30 -07:00
parent 8bc8b1087c
commit 80d6be9849
6 changed files with 60 additions and 25 deletions

View file

@ -91,7 +91,7 @@ func GetDefaultSeriesStrokeColor(index int) color.RGBA {
var ( var (
// DefaultFinalLabelPadding is the padding around the final label. // DefaultFinalLabelPadding is the padding around the final label.
DefaultFinalLabelPadding = Box{Top: 5, Left: 0, Right: 5, Bottom: 5} DefaultFinalLabelPadding = Box{Top: 5, Left: 0, Right: 7, Bottom: 5}
// DefaultBackgroundPadding is the default canvas padding config. // DefaultBackgroundPadding is the default canvas padding config.
DefaultBackgroundPadding = Box{Top: 5, Left: 5, Right: 5, Bottom: 5} DefaultBackgroundPadding = Box{Top: 5, Left: 5, Right: 5, Bottom: 5}
) )

View file

@ -3,7 +3,4 @@ package drawing
const ( const (
// DefaultDPI is the default image DPI. // DefaultDPI is the default image DPI.
DefaultDPI = 96.0 DefaultDPI = 96.0
// EMRatio is the ratio of something to something else.
EMRatio = 64.0 / 72.0
) )

View file

@ -149,9 +149,8 @@ func (rgc *RasterGraphicContext) CreateStringPath(s string, x, y float64) (curso
return return
} }
// GetStringBounds returns the approximate pixel bounds of a string. // GetStringBounds returns the approximate points bounds of a string.
// The the left edge of the em square of the first character of s // It will be required to convert points to pixels for measurement.
// and the baseline intersect at 0, 0 in the returned coordinates.
func (rgc *RasterGraphicContext) GetStringBounds(s string) (left, top, right, bottom float64, err error) { func (rgc *RasterGraphicContext) GetStringBounds(s string) (left, top, right, bottom float64, err error) {
f := rgc.GetFont() f := rgc.GetFont()
if f == nil { if f == nil {
@ -192,7 +191,7 @@ func (rgc *RasterGraphicContext) GetStringBounds(s string) (left, top, right, bo
// recalc recalculates scale and bounds values from the font size, screen // recalc recalculates scale and bounds values from the font size, screen
// resolution and font metrics, and invalidates the glyph cache. // resolution and font metrics, and invalidates the glyph cache.
func (rgc *RasterGraphicContext) recalc() { func (rgc *RasterGraphicContext) recalc() {
rgc.current.Scale = rgc.current.FontSize * float64(rgc.DPI) * EMRatio rgc.current.Scale = rgc.current.FontSizePoints * float64(rgc.DPI)
} }
// SetFont sets the font used to draw text. // SetFont sets the font used to draw text.
@ -206,8 +205,8 @@ func (rgc *RasterGraphicContext) GetFont() *truetype.Font {
} }
// SetFontSize sets the font size in points (as in ``a 12 point font''). // SetFontSize sets the font size in points (as in ``a 12 point font'').
func (rgc *RasterGraphicContext) SetFontSize(fontSize float64) { func (rgc *RasterGraphicContext) SetFontSize(fontSizePoints float64) {
rgc.current.FontSize = fontSize rgc.current.FontSizePoints = fontSizePoints
rgc.recalc() rgc.recalc()
} }

View file

@ -25,7 +25,7 @@ type ContextStack struct {
Cap LineCap Cap LineCap
Join LineJoin Join LineJoin
FontSize float64 FontSizePoints float64
Font *truetype.Font Font *truetype.Font
Scale float64 Scale float64
@ -45,118 +45,145 @@ func NewStackGraphicContext() *StackGraphicContext {
gc.current.Cap = RoundCap gc.current.Cap = RoundCap
gc.current.FillRule = FillRuleEvenOdd gc.current.FillRule = FillRuleEvenOdd
gc.current.Join = RoundJoin gc.current.Join = RoundJoin
gc.current.FontSize = 10 gc.current.FontSizePoints = 10
return gc return gc
} }
// GetMatrixTransform returns the matrix transform.
func (gc *StackGraphicContext) GetMatrixTransform() Matrix { func (gc *StackGraphicContext) GetMatrixTransform() Matrix {
return gc.current.Tr return gc.current.Tr
} }
func (gc *StackGraphicContext) SetMatrixTransform(Tr Matrix) { // SetMatrixTransform sets the matrix transform.
gc.current.Tr = Tr func (gc *StackGraphicContext) SetMatrixTransform(tr Matrix) {
gc.current.Tr = tr
} }
func (gc *StackGraphicContext) ComposeMatrixTransform(Tr Matrix) { // ComposeMatrixTransform composes a transform into the current transform.
gc.current.Tr.Compose(Tr) func (gc *StackGraphicContext) ComposeMatrixTransform(tr Matrix) {
gc.current.Tr.Compose(tr)
} }
// Rotate rotates the matrix transform by an angle in degrees.
func (gc *StackGraphicContext) Rotate(angle float64) { func (gc *StackGraphicContext) Rotate(angle float64) {
gc.current.Tr.Rotate(angle) gc.current.Tr.Rotate(angle)
} }
// Translate translates a transform.
func (gc *StackGraphicContext) Translate(tx, ty float64) { func (gc *StackGraphicContext) Translate(tx, ty float64) {
gc.current.Tr.Translate(tx, ty) gc.current.Tr.Translate(tx, ty)
} }
// Scale scales a transform.
func (gc *StackGraphicContext) Scale(sx, sy float64) { func (gc *StackGraphicContext) Scale(sx, sy float64) {
gc.current.Tr.Scale(sx, sy) gc.current.Tr.Scale(sx, sy)
} }
// SetStrokeColor sets the stroke color.
func (gc *StackGraphicContext) SetStrokeColor(c color.Color) { func (gc *StackGraphicContext) SetStrokeColor(c color.Color) {
gc.current.StrokeColor = c gc.current.StrokeColor = c
} }
// SetFillColor sets the fill color.
func (gc *StackGraphicContext) SetFillColor(c color.Color) { func (gc *StackGraphicContext) SetFillColor(c color.Color) {
gc.current.FillColor = c gc.current.FillColor = c
} }
// SetFillRule sets the fill rule.
func (gc *StackGraphicContext) SetFillRule(f FillRule) { func (gc *StackGraphicContext) SetFillRule(f FillRule) {
gc.current.FillRule = f gc.current.FillRule = f
} }
// SetLineWidth sets the line width.
func (gc *StackGraphicContext) SetLineWidth(lineWidth float64) { func (gc *StackGraphicContext) SetLineWidth(lineWidth float64) {
gc.current.LineWidth = lineWidth gc.current.LineWidth = lineWidth
} }
// SetLineCap sets the line cap.
func (gc *StackGraphicContext) SetLineCap(cap LineCap) { func (gc *StackGraphicContext) SetLineCap(cap LineCap) {
gc.current.Cap = cap gc.current.Cap = cap
} }
// SetLineJoin sets the line join.
func (gc *StackGraphicContext) SetLineJoin(join LineJoin) { func (gc *StackGraphicContext) SetLineJoin(join LineJoin) {
gc.current.Join = join gc.current.Join = join
} }
// SetLineDash sets the line dash.
func (gc *StackGraphicContext) SetLineDash(dash []float64, dashOffset float64) { func (gc *StackGraphicContext) SetLineDash(dash []float64, dashOffset float64) {
gc.current.Dash = dash gc.current.Dash = dash
gc.current.DashOffset = dashOffset gc.current.DashOffset = dashOffset
} }
func (gc *StackGraphicContext) SetFontSize(fontSize float64) { // SetFontSize sets the font size.
gc.current.FontSize = fontSize func (gc *StackGraphicContext) SetFontSize(fontSizePoints float64) {
gc.current.FontSizePoints = fontSizePoints
} }
// GetFontSize gets the font size.
func (gc *StackGraphicContext) GetFontSize() float64 { func (gc *StackGraphicContext) GetFontSize() float64 {
return gc.current.FontSize return gc.current.FontSizePoints
} }
// SetFont sets the current font.
func (gc *StackGraphicContext) SetFont(f *truetype.Font) { func (gc *StackGraphicContext) SetFont(f *truetype.Font) {
gc.current.Font = f gc.current.Font = f
} }
// GetFont returns the font.
func (gc *StackGraphicContext) GetFont() *truetype.Font { func (gc *StackGraphicContext) GetFont() *truetype.Font {
return gc.current.Font return gc.current.Font
} }
// BeginPath starts a new path.
func (gc *StackGraphicContext) BeginPath() { func (gc *StackGraphicContext) BeginPath() {
gc.current.Path.Clear() gc.current.Path.Clear()
} }
// IsEmpty returns if the path is empty.
func (gc *StackGraphicContext) IsEmpty() bool { func (gc *StackGraphicContext) IsEmpty() bool {
return gc.current.Path.IsEmpty() return gc.current.Path.IsEmpty()
} }
func (gc *StackGraphicContext) LastPoint() (float64, float64) { // LastPoint returns the last point on the path.
func (gc *StackGraphicContext) LastPoint() (x float64, y float64) {
return gc.current.Path.LastPoint() return gc.current.Path.LastPoint()
} }
// MoveTo moves the cursor for a path.
func (gc *StackGraphicContext) MoveTo(x, y float64) { func (gc *StackGraphicContext) MoveTo(x, y float64) {
gc.current.Path.MoveTo(x, y) gc.current.Path.MoveTo(x, y)
} }
// LineTo draws a line.
func (gc *StackGraphicContext) LineTo(x, y float64) { func (gc *StackGraphicContext) LineTo(x, y float64) {
gc.current.Path.LineTo(x, y) gc.current.Path.LineTo(x, y)
} }
// QuadCurveTo draws a quad curve.
func (gc *StackGraphicContext) QuadCurveTo(cx, cy, x, y float64) { func (gc *StackGraphicContext) QuadCurveTo(cx, cy, x, y float64) {
gc.current.Path.QuadCurveTo(cx, cy, x, y) gc.current.Path.QuadCurveTo(cx, cy, x, y)
} }
// CubicCurveTo draws a cubic curve.
func (gc *StackGraphicContext) CubicCurveTo(cx1, cy1, cx2, cy2, x, y float64) { func (gc *StackGraphicContext) CubicCurveTo(cx1, cy1, cx2, cy2, x, y float64) {
gc.current.Path.CubicCurveTo(cx1, cy1, cx2, cy2, x, y) gc.current.Path.CubicCurveTo(cx1, cy1, cx2, cy2, x, y)
} }
// ArcTo draws an arc.
func (gc *StackGraphicContext) ArcTo(cx, cy, rx, ry, startAngle, angle float64) { func (gc *StackGraphicContext) ArcTo(cx, cy, rx, ry, startAngle, angle float64) {
gc.current.Path.ArcTo(cx, cy, rx, ry, startAngle, angle) gc.current.Path.ArcTo(cx, cy, rx, ry, startAngle, angle)
} }
// Close closes a path.
func (gc *StackGraphicContext) Close() { func (gc *StackGraphicContext) Close() {
gc.current.Path.Close() gc.current.Path.Close()
} }
// Save pushes a context onto the stack.
func (gc *StackGraphicContext) Save() { func (gc *StackGraphicContext) Save() {
context := new(ContextStack) context := new(ContextStack)
context.FontSize = gc.current.FontSize context.FontSizePoints = gc.current.FontSizePoints
context.Font = gc.current.Font context.Font = gc.current.Font
context.LineWidth = gc.current.LineWidth context.LineWidth = gc.current.LineWidth
context.StrokeColor = gc.current.StrokeColor context.StrokeColor = gc.current.StrokeColor
@ -174,6 +201,7 @@ func (gc *StackGraphicContext) Save() {
gc.current = context gc.current = context
} }
// Restore restores the previous context.
func (gc *StackGraphicContext) Restore() { func (gc *StackGraphicContext) Restore() {
if gc.current.Previous != nil { if gc.current.Previous != nil {
oldContext := gc.current oldContext := gc.current

View file

@ -9,6 +9,18 @@ import (
"github.com/golang/freetype/truetype" "github.com/golang/freetype/truetype"
) )
// PixelsToPoints returns the points for a given number of pixels at a DPI.
func PixelsToPoints(dpi, pixels float64) (points float64) {
points = (pixels * 72.0) / dpi
return
}
// PointsToPixels returns the pixels for a given number of points at a DPI.
func PointsToPixels(dpi, points float64) (pixels float64) {
pixels = (points * dpi) / 72.0
return
}
func abs(i int) int { func abs(i int) int {
if i < 0 { if i < 0 {
return -i return -i

View file

@ -5,7 +5,6 @@ import (
"image/color" "image/color"
"image/png" "image/png"
"io" "io"
"math"
"github.com/golang/freetype/truetype" "github.com/golang/freetype/truetype"
"github.com/wcharczuk/go-chart/drawing" "github.com/wcharczuk/go-chart/drawing"
@ -130,8 +129,8 @@ func (rr *rasterRenderer) MeasureText(body string) (width int, height int) {
} }
dw := r - l dw := r - l
dh := b - t dh := b - t
width = int(math.Ceil(dw * (4.0 / 3.0))) width = int(drawing.PointsToPixels(rr.gc.GetDPI(), dw))
height = int(math.Ceil(dh * (4.0 / 3.0))) height = int(drawing.PointsToPixels(rr.gc.GetDPI(), dh))
return return
} }