43 lines
912 B
Go
43 lines
912 B
Go
package chart
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import (
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"bytes"
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"errors"
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"image"
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"image/png"
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)
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// RGBACollector is a render target for a chart.
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type RGBACollector interface {
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SetRGBA(i *image.RGBA)
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}
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// ImageWriter is a special type of io.Writer that produces a final image.
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type ImageWriter struct {
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rgba *image.RGBA
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contents *bytes.Buffer
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}
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func (ir *ImageWriter) Write(buffer []byte) (int, error) {
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if ir.contents == nil {
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ir.contents = bytes.NewBuffer([]byte{})
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}
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return ir.contents.Write(buffer)
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}
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// SetRGBA sets a raw version of the image.
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func (ir *ImageWriter) SetRGBA(i *image.RGBA) {
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ir.rgba = i
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}
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// Image returns an *image.Image for the result.
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func (ir *ImageWriter) Image() (image.Image, error) {
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if ir.rgba != nil {
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return ir.rgba, nil
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}
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if ir.contents != nil && ir.contents.Len() > 0 {
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return png.Decode(ir.contents)
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}
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return nil, errors.New("no valid sources for image data, cannot continue")
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}
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