WriteableBitmap.Unlock 方法

定义

命名空间:

System.Windows.Media.Imaging

程序集:

PresentationCore.dll

释放后台缓冲区，以使之可用于显示。

public:
 void Unlock();

public void Unlock ();

member this.Unlock : unit -> unit

Public Sub Unlock ()

例外

InvalidOperationException

对 Lock() 或 TryLock(Duration) 方法的调用未锁定位图。

示例

下面的代码示例演示如何使用 Unlock 方法释放回缓冲区。

    // The DrawPixel method updates the WriteableBitmap by using
    // unsafe code to write a pixel into the back buffer.
    static void DrawPixel(MouseEventArgs e)
    {
        int column = (int)e.GetPosition(i).X;
        int row = (int)e.GetPosition(i).Y;

        try{
            // Reserve the back buffer for updates.
            writeableBitmap.Lock();

            unsafe
            {
                // Get a pointer to the back buffer.
                IntPtr pBackBuffer = writeableBitmap.BackBuffer;

                // Find the address of the pixel to draw.
                pBackBuffer += row * writeableBitmap.BackBufferStride;
                pBackBuffer += column * 4;

                // Compute the pixel's color.
                int color_data = 255 << 16; // R
                color_data |= 128 << 8;   // G
                color_data |= 255 << 0;   // B

                // Assign the color data to the pixel.
                *((int*) pBackBuffer) = color_data;
            }

            // Specify the area of the bitmap that changed.
            writeableBitmap.AddDirtyRect(new Int32Rect(column, row, 1, 1));
        }
        finally{
            // Release the back buffer and make it available for display.
            writeableBitmap.Unlock();
        }
    }

注解

方法 Unlock 递减锁计数。 当锁计数达到 0 时，如果已调用 方法， AddDirtyRect 则会请求呈现传递。

另请参阅

• Lock()
• AddDirtyRect(Int32Rect)