在我的应用程序中,我想实现二级磁贴,以便用户可以直接访问应用程序的特定部分,并显示该磁贴上的特定部分信息。
对于平铺图像,我想使用将直接访问的部分的图标,但我只能访问直接从网络链接下载的正方形大小的图像(在创建平铺时)。由于我没有宽瓷砖的图像,我尝试用透明边框填充它们,以创建宽瓷砖。我使用了WritableBitmapEx库,但我的代码导致了AccessViolationException。
StorageFile file = await ApplicationData.Current.TemporaryFolder.GetFileAsync(tempFileName);
IRandomAccessStream fileStream = await file.OpenAsync(Windows.Storage.FileAccessMode.ReadWrite);
WriteableBitmap bitmap = new WriteableBitmap(150, 150);
await bitmap.SetSourceAsync(fileStream);
WriteableBitmap bitmapDummy = BitmapFactory.New(310, 150);
using (bitmapDummy.GetBitmapContext())
{
using (bitmap.GetBitmapContext())
{
bitmapDummy.Blit(new Rect(80.0, 0.0, 150, 150), bitmap, new Rect(0.0, 0.0, 150, 150), WriteableBitmapExtensions.BlendMode.None);
}
}
异常发生在CCD_ 1上,因此我无法创建图像。
我在这里尝试做的是创建一个空的宽瓷砖图像,并将方形瓷砖图像放在中间
最后,我也想将图像转换为透明的PNG,但这是另一个问题,因为我还不知道如何创建位图。
感谢您提前提供的帮助。
我在这里找到了解决方案。在我尝试访问该图像之前,它似乎没有加载到WriteableBitmap中,因此引发了AccessViolationException。因此,
WriteableBitmap bitmap = new WriteableBitmap(150, 150);
await bitmap.SetSourceAsync(fileStream);
我开始使用
WriteableBitmap bitmap = await BitmapFactory.New(1, 1).FromStream(fileStream);
现在问题解决了。
下面是为那些发现这个问题的人调整和填充方形图像的完整代码。
public static async Task PadPngImage(StorageFile inputFile, StorageFile outputFile, uint width, uint height, uint boundingBoxWidth, uint boundingBoxHeight)
{
// Resize the input image
StorageFile temporaryFile = await ApplicationData.Current.TemporaryFolder.CreateFileAsync("PadImageTemporaryFile.png", CreationCollisionOption.ReplaceExisting);
await ResizeImage(inputFile, temporaryFile, width, height);
// Create a stream linked to resized image
using (IRandomAccessStream temporaryFileStream = await temporaryFile.OpenAsync(Windows.Storage.FileAccessMode.ReadWrite))
{
WriteableBitmap bitmap = await BitmapFactory.New(1, 1).FromStream(temporaryFileStream);
// Create an empty image with specified bounding dimentions
WriteableBitmap bitmapDummy = BitmapFactory.New((int)boundingBoxWidth, (int)boundingBoxHeight);
using (bitmapDummy.GetBitmapContext())
{
using (bitmap.GetBitmapContext())
{
// Calculate position of the image
Rect center = new Rect((boundingBoxWidth - width) / 2, (boundingBoxHeight - height) / 2, width, height);
bitmapDummy.Blit(center, bitmap, new Rect(0.0, 0.0, width, height), WriteableBitmapExtensions.BlendMode.None);
}
}
using(IRandomAccessStream stream = await outputFile.OpenAsync(Windows.Storage.FileAccessMode.ReadWrite))
{
await bitmapDummy.ToStream(stream, BitmapEncoder.PngEncoderId);
}
}
}
public static async Task ResizeImage(StorageFile inputFile, StorageFile outputFile, uint newWidth, uint newHeight)
{
// Input Stream & Decoder
using (IRandomAccessStream fileStream = await inputFile.OpenAsync(Windows.Storage.FileAccessMode.Read))
{
BitmapDecoder decoder = await BitmapDecoder.CreateAsync(fileStream);
// Output Stream & Encoder
using (IRandomAccessStream stream = await outputFile.OpenAsync(Windows.Storage.FileAccessMode.ReadWrite))
{
BitmapEncoder encoder = await BitmapEncoder.CreateForTranscodingAsync(stream, decoder);
// Scale the bitmap image
encoder.BitmapTransform.ScaledWidth = newWidth;
encoder.BitmapTransform.ScaledHeight = newHeight;
encoder.BitmapTransform.InterpolationMode = BitmapInterpolationMode.Fant;
await encoder.FlushAsync();
}
}
}