wp中的位图

        //

        // 摘要:

        //     使用提供的元素和变换初始化 System.Windows.Media.Imaging.WriteableBitmap 类的新实例。

        //

        // 参数:

        //   element:

        //     要在位图中呈现的所需元素。

        //

        //   transform:

        //     用户要在绘制到位图中之前的最后一步中应用到元素的变换。如果您希望位图将它的变换考虑在内，则这对于您特别有意义。此值可以为 null。

        //

        // 异常:

        //   System.ArgumentNullException:

        //     element 为 null。

        //

        //   System.ArgumentException:

        //     元素大小无效。当像素宽度或像素高度不大于零时，发生这种情况。

        [SecuritySafeCritical]

        public WriteableBitmap(UIElement element, Transform transform);

View Code

public WriteableBitmap(UIElement element, Transform transform);

将某元素通过变换，绘出其形状。 

获取照相机中的图片，进行重绘

void OnPhotoChooserCompleted(object sender, PhotoResult args)

        {

            if (args.Error != null || args.ChosenPhoto == null)

                return;



            BitmapImage bitmapImage = new BitmapImage();

            bitmapImage.SetSource(args.ChosenPhoto);



            Image imgBase = new Image();

            imgBase.Source = bitmapImage;

            imgBase.Stretch = Stretch.None;



            // Upper-left

            WriteableBitmap writeableBitmap = 

                new WriteableBitmap(bitmapImage.PixelWidth / 2,

                                    bitmapImage.PixelHeight / 2);

            writeableBitmap.Render(imgBase, null);

            writeableBitmap.Invalidate();

            imgUL.Source = writeableBitmap;



            // Upper-right

            writeableBitmap = new WriteableBitmap(bitmapImage.PixelWidth / 2,

                                                  bitmapImage.PixelHeight / 2);

            TranslateTransform translate = new TranslateTransform();

            translate.X = -bitmapImage.PixelWidth / 2;

            //在位图上呈现元素

            writeableBitmap.Render(imgBase, translate);

            //对位图进行重绘

            writeableBitmap.Invalidate();

            imgUR.Source = writeableBitmap;



            // Lower-left

            writeableBitmap = new WriteableBitmap(bitmapImage.PixelWidth / 2,

                                                  bitmapImage.PixelHeight / 2);

            translate.X = 0;

            translate.Y = -bitmapImage.PixelHeight / 2;

            writeableBitmap.Render(imgBase, translate);

            writeableBitmap.Invalidate();

            imgLL.Source = writeableBitmap;



            // Lower-right

            writeableBitmap = new WriteableBitmap(bitmapImage.PixelWidth / 2,

                                                  bitmapImage.PixelHeight / 2);

            translate.X = -bitmapImage.PixelWidth / 2;

            writeableBitmap.Render(imgBase, translate);

            writeableBitmap.Invalidate();

            imgLR.Source = writeableBitmap;



            txtblk.Visibility = Visibility.Collapsed;

        }