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我是MonoTouch的新手,最近我将代码从标准C#转换为符合MonoTouch的代码,因此可以在iPhone应用程序中使用它。我已经成功地转换代码,但是我碰到的这种方法的一个问题,我用它来返回一个位图背景:MonoTouch中的CGBitmapContext抛出无效的句柄异常
private CGBitmapContext ExtractWriteableBitmap(RGBPaletteRecord rgbPalette, double dpi, ChartIndexFile indexFile, RasterChartFile chartFile)
{
CGBitmapContext bitmapImage = null;
TileRecord tile;
// calc the number of tiles in each plane
int tileCountX = indexFile.TileIndexRecords.Max(ti => ti.X);
int tileCountY = indexFile.TileIndexRecords.Max(ti => ti.Y);
// create the big picture
int pixelWidth = (tileCountX + 1) * TileRecord.PixelWidth;
int pixelHeight = (tileCountY + 1) * TileRecord.PixelHight;
int intDPI = Convert.ToInt32(dpi);
int bytesPerRow = (int)TileRecord.PixelWidth * 4; // note that bytes per row should
//be based on width, not height.
CGColorSpace colorSpace = CGColorSpace.CreateDeviceRGB();
CGImageAlphaInfo info = CGImageAlphaInfo.NoneSkipFirst;
// create the big picture
bitmapImage = new CGBitmapContext(System.IntPtr.Zero, pixelWidth, pixelHeight, intDPI, intDPI, colorSpace, info);
byte[] sourceArray;
RectangleF sourceRect;
//copy the tiles into the big picture
int index = 0;
foreach (TileIndexRecord tileIndexRecord in indexFile.TileIndexRecords)
{
// get the tile record
tile = chartFile.TileRecords[index];
// extract the byte array for the given palette
sourceArray = tile.GetBytes(rgbPalette);
GCHandle pinnedArray = GCHandle.Alloc(sourceArray, GCHandleType.Pinned);
IntPtr pointer = pinnedArray.AddrOfPinnedObject();
//do your stuff
//pinnedArray.Free();
CGImage image = new CGImage(pointer);
sourceRect = new RectangleF(0, 0, TileRecord.PixelWidth, TileRecord.PixelHight);
bitmapImage.DrawImage(new RectangleF(0,0,128,128),image);
// copy the tile image into the big picture
//bitmapImage.WritePixels(sourceRect, sourceArray, TileRecord.Stride, (tileIndexRecord.X * TileRecord.PixelWidth), (tileIndexRecord.Y * TileRecord.PixelHight));
// increment the index
index++;
}
return bitmapImage;
}
这里是堆栈跟踪:
System.Exception: Invalid handle
at MonoTouch.CoreGraphics.CGContext..ctor (IntPtr handle, Boolean owns) [0x00022] in /Developer/MonoTouch/Source/monotouch/src/shared/CoreGraphics/CGContext.cs:136
at MonoTouch.CoreGraphics.CGBitmapContext..ctor (IntPtr data, Int32 width, Int32 height, Int32 bitsPerComponent, Int32 bytesPerRow, MonoTouch.CoreGraphics.CGColorSpace colorSpace, CGImageAlphaInfo bitmapInfo) [0x00000] in <filename unknown>:0
at Jargoon.Data.Arcs.Loader.ExtractWriteableBitmap (Jargoon.Data.Arcs.Records.RGBPaletteRecord rgbPalette, Double dpi, Jargoon.Data.Arcs.Raschts.ChartIndexFile indexFile, Jargoon.Data.Arcs.Raschts.RasterChartFile chartFile) [0x00079] in /Users/jacknutkins/Desktop/Jargoon/ARCSViewer/ARCSViewer/Loader.cs:569
at Jargoon.Data.Arcs.Loader.GetHiResImage (Jargoon.Data.Arcs.Records.RGBPaletteRecord rgbPalette) [0x00000] in /Users/jacknutkins/Desktop/Jargoon/ARCSViewer/ARCSViewer/Loader.cs:361
at ARCSViewer.ARCSViewerViewController.ViewDidLoad() [0x0001c] in /Users/jacknutkins/Desktop/Jargoon/ARCSViewer/ARCSViewer/ARCSViewerViewController.cs:37
at (wrapper managed-to-native) MonoTouch.UIKit.UIApplication:UIApplicationMain (int,string[],intptr,intptr)
at MonoTouch.UIKit.UIApplication.Main (System.String[] args, System.String principalClassName, System.String delegateClassName) [0x00042] in /Developer/MonoTouch/Source/monotouch/src/UIKit/UIApplication.cs:29
at ARCSViewer.Application.Main (System.String[] args) [0x00000] in /Users/jacknutkins/Desktop/Jargoon/ARCSViewer/ARCSViewer/Main.cs:17
的错误发生在该行:
// create the big picture
bitmapImage = new CGBitmapContext(System.IntPtr.Zero, pixelWidth, pixelHeight, intDPI, intDPI, colorSpace, info);
我很新的MonoTouch的,所以如果它已经昭然若揭了尝试,并承担与我,但任何人都可以解释怎么回事?
为输入而欢呼,我编辑了问题与我得到的其他堆栈跟踪,我将如何去释放上下文?欢呼声 –
第一次调用这段代码或经过多次迭代后是否发生异常?你传递给CGBitmapContext构造函数的参数是什么(如果你尝试创建一个比例太大的位图,它会失败) –
这就是问题(方式太大),昨晚我设法弄清楚了,非常感谢。 –