用xgb和freetype-go建立窗口并画图

shikuijie · · 4621 次点击 · 开始浏览    置顶
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最近一直在鼓捣怎样用golang画图(不想用cgo来封装c库),终于找到了xgb和freetype-go。 xgb可以用来创建窗口,freetype-go中的raster库可以用来画图。 下面我用它们写了一个简单的程序,它在窗口中画了个90度的扇形 package main import ( "code.google.com/p/freetype-go/freetype/raster" "fmt" "github.com/BurntSushi/xgbutil" "github.com/BurntSushi/xgbutil/xevent" "github.com/BurntSushi/xgbutil/xgraphics" "github.com/BurntSushi/xgbutil/xwindow" "image" "image/color" "image/png" "os" ) func main() { // width and height of the window to be created w, h := 400, 400 // xu communicates with X server xu, err := xgbutil.NewConn() if err != nil { fmt.Println(err) return } // just create a id for the window xwin, err := xwindow.Generate(xu) if err != nil { fmt.Println(err) return } // now, create the window err = xwin.CreateChecked( xu.RootWin(), // parent window 0, 0, w, h, // window size 0) // related to event, not considered here if err != nil { fmt.Println(err) return } // now we can see the window on the screen xwin.Map() // 'rstr' calculates the data needed to draw // 'painter' draw with the data on 'canvas' canvas := image.NewRGBA(image.Rect(0, 0, w, h)) rstr := raster.NewRasterizer(w, h) painter := raster.NewRGBAPainter(canvas) painter.SetColor(color.RGBA{0xff, 0xff, 0x00, 0xff}) // specify the start point (100, 100) // why shift by 8? // raster.Point has 2 memembers X and Y, they are both of type raster.Fix32 // raster.Fix32 is fixed point number, the high 24 bits is the integral part // for example, a raster.Fix32 number 1 in fact is 1/256 a := raster.Point{100 << 8, 100 << 8} rstr.Start(a) // draw a straight line from the start point b := raster.Point{200 << 8, 100 << 8} rstr.Add1(b) // draw a bezier curve, points b, c, d are the control points c := raster.Point{200 << 8, 200 << 8} d := raster.Point{100 << 8, 200 << 8} rstr.Add2(c, d) rstr.Add1(a) // now, draw the shape on 'canvas' rstr.Rasterize(painter) // 'canvas' is of type *image.RGBA, // but the window need xgraphics.Image to show, so we convert it ximg := xgraphics.NewConvert(xu, canvas) // I want 'ximg' to show on 'xwin' ximg.XSurfaceSet(xwin.Id) // now show it ximg.XDraw() ximg.XPaint(xwin.Id) // save the image to png fd, err := os.Create("blog.png") if err != nil { fmt.Println(err) return } err = png.Encode(fd, canvas) if err != nil { fmt.Println(err) } // listen on the events such as keypress, mousepress etc. xevent.Main(xu) } [1]: http:///home/shikuijie/blog.png

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