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More Area API planning.

This commit is contained in:
Pietro Gagliardi 2014-03-14 08:43:18 -04:00
parent 85f6b63c12
commit 43da1118be
1 changed files with 28 additions and 1 deletions
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areaplan.md
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@ -88,7 +88,7 @@ GpStatus WINGDIPAPI GdipDrawImageI(GpGraphics *graphics, GpImage *image, INT x,
GpStatus WINGDIPAPI GdipDeleteGraphics(GpGraphics *graphics);
GpStatus WINGDIPAPI GdipDisposeImage(GpImage *image);
```
(`GpBitmap` extends `GpImage`.) The only problem is the pixel format: the most appropriate one is `PixelFormat32bppARGB`, which is not premultiplied, but the components are in the wrong order... (there is no RGBA pixel format in any bit width) (TODO `GdipDisposeImage` seems wrong since it bypasses `~Bitmap()` and goes right for `~Image()` but I don't see an explicit `~Bitmap()`...)
(`GpBitmap` extends `GpImage`.) The only problem is the pixel format: the most appropriate one is `PixelFormat32bppARGB`, which is not premultiplied, but the components are in the wrong order... (specifically in BGRA order) (there is no RGBA pixel format in any bit width) (TODO `GdipDisposeImage` seems wrong since it bypasses `~Bitmap()` and goes right for `~Image()` but I don't see an explicit `~Bitmap()`...)
Disregarding the RGBA issue, the draw code would be
```go
@ -122,6 +122,33 @@ Disregarding the RGBA issue, the draw code would be
}
```
Upon further review, there really doesn't seem to be any way around it: we have to shuffle the image data around. We seem to be in good company: [go.wde needs to do so as well](https://github.com/skelterjohn/go.wde/blob/master/win/dib_windows.go). But you can't be too sure...
```go
realbits := make([]byte, 4 * i.Rect.Dx() * I.Rect.Dy())
q := 0
for y := i.Rect.Min.Y; y < i.Rect.Max.Y; y++ {
k := i.Pix[y * i.Stride:]
for x := i.Rect.Min.X; x < i.Rect.Max.X; x += 4 {
realbits[q + 0] = byte(k[y + x + 2]) // B
realbits[q + 1] = byte(k[y + x + 1]) // G
realbits[q + 2] = byte(k[y + x + 0]) // R
realbits[q + 3] = byte(k[y + x + 3]) // A
q += 4
}
}
var bitmap, graphics uintptr
status := GdipCreateBitmapFromScan0(
i.Rect.Dx(),
i.Rect.Dy(),
0, // no stride anymore
PixelFormat32bppARGB,
&realbits[0],
&bitmap)
// rest of code
```
We must also initialize and shut down GDI+ in uitask:
```go
var (