a80e3778fd
to support high DPI scaling, use the FramebufferSize functions in glfwcanvas and sdlcanvas to determine the canvas size
134 lines
2.9 KiB
Go
134 lines
2.9 KiB
Go
package main
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import (
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"image/color"
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"log"
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"math"
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"github.com/tfriedel6/canvas/sdlcanvas"
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)
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func main() {
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wnd, cv, err := sdlcanvas.CreateWindow(1280, 720, "Canvas Example")
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if err != nil {
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log.Println(err)
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return
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}
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defer wnd.Destroy()
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lg := cv.CreateLinearGradient(320, 200, 480, 520)
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lg.AddColorStop(0, "#ff000040")
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lg.AddColorStop(1, "#00ff0040")
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lg.AddColorStop(0.5, "#0000ff40")
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rg := cv.CreateRadialGradient(540, 300, 80, 740, 300, 100)
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rg.AddColorStop(0, "#ff0000")
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rg.AddColorStop(1, "#00ff00")
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rg.AddColorStop(0.5, "#0000ff")
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wnd.MainLoop(func() {
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w, h := float64(cv.Width()), float64(cv.Height())
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// Clear the screen
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cv.SetFillStyle("#000")
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cv.FillRect(0, 0, w, h)
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// Estimated size used for scaling
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const (
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contentWidth = 1000
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contentHeight = 350
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)
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// Calculate scaling
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sx := w / contentWidth
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sy := h / contentHeight
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scale := math.Min(sx, sy)
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cv.Save()
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defer cv.Restore()
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cv.Scale(scale, scale)
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// Draw lines with different colors and line thickness
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for x := 1.0; x < 10.5; x += 1.0 {
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cv.SetStrokeStyle(int(x*25), 255, 255)
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cv.SetLineWidth(x)
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cv.BeginPath()
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cv.MoveTo(x*10+20, 20)
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cv.LineTo(x*10+20, 120)
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cv.Stroke()
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}
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// Draw a path
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cv.BeginPath()
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cv.MoveTo(160, 20)
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cv.LineTo(180, 20)
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cv.LineTo(180, 40)
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cv.LineTo(200, 40)
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cv.LineTo(200, 60)
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cv.LineTo(220, 60)
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cv.LineTo(220, 80)
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cv.LineTo(240, 80)
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cv.LineTo(240, 100)
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cv.LineTo(260, 100)
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cv.LineTo(260, 120)
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cv.ArcTo(160, 120, 160, 100, 20)
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cv.ClosePath()
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cv.SetStrokeStyle(color.RGBA{R: 255, G: 128, B: 128, A: 255})
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cv.SetLineWidth(4)
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cv.Stroke()
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// Fill a polygon
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cv.BeginPath()
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cv.MoveTo(300, 20)
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cv.LineTo(340, 20)
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cv.QuadraticCurveTo(370, 20, 370, 50)
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cv.QuadraticCurveTo(370, 80, 400, 80)
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cv.LineTo(400, 80)
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cv.LineTo(400, 120)
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cv.LineTo(360, 120)
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cv.BezierCurveTo(330, 120, 330, 80, 300, 80)
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cv.ClosePath()
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cv.SetFillStyle(color.RGBA{R: 128, G: 255, B: 128, A: 255})
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cv.Fill()
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// Draw with alpha
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cv.SetGlobalAlpha(0.5)
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cv.SetFillStyle("#FF0000")
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cv.BeginPath()
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cv.Arc(100, 275, 60, 0, math.Pi*2, false)
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cv.Fill()
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cv.SetFillStyle("#00FF00")
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cv.BeginPath()
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cv.Arc(140, 210, 60, 0, math.Pi*2, false)
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cv.Fill()
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cv.SetFillStyle("#0000FF")
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cv.BeginPath()
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cv.Arc(180, 275, 60, 0, math.Pi*2, false)
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cv.Fill()
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cv.SetGlobalAlpha(1)
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// Clipped drawing
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cv.Save()
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cv.BeginPath()
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cv.Arc(340, 240, 80, 0, math.Pi*2, true)
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cv.Clip()
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cv.SetStrokeStyle(0, 255, 0)
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for x := 1.0; x < 12.5; x += 1.0 {
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cv.BeginPath()
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cv.MoveTo(260, 140+16*x)
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cv.LineTo(420, 140+16*x)
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cv.Stroke()
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}
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cv.SetFillStyle(0, 0, 255)
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for x := 1.0; x < 12.5; x += 1.0 {
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cv.FillRect(246+x*14, 150, 6, 180)
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}
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cv.Restore()
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// Draw images
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cv.DrawImage("cat.jpg", 480, 40, 320, 265)
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// Draw text
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cv.SetFont("Righteous-Regular.ttf", 40)
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cv.FillText("<-- Cat", 820, 180)
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})
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}
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