使用MSDN示例错误的使用gif动画进行矩形绘制

Question

我有一个gif动画。当我在CompactFramework中工作时，我遵循this MSDN example。

基本的想法是将帧添加到图像，并用下一帧重画rectangle，创建动画。除了动画以正方形显示，而不是我的图像的全尺寸（240,320）之外，它工作得很好。

这是我的代码：

一类AnimateCtl.cs

：

public class AnimateCtl : System.Windows.Forms.Control 
{ 
    Timer fTimer; 
    int frameWidth = 240; 
    int frameHeight = 320; 
    int loopCount = 0; 
    int loopCounter = 0; 
    int frameCount; 
    int currentFrame = 0; 
    Graphics graphics; 

    private Bitmap bitmap; 
    public Bitmap Bitmap 
    { 
     get 
     { 
      return bitmap; 
     } 
     set 
     { 
      bitmap = value; 
     } 
    } 

    private void Draw(int iframe) 
    { 
     //Calculate the left location of the drawing frame 
     int XLocation = iframe * frameWidth; 

     Rectangle rect = new Rectangle(XLocation, 0, frameWidth, frameHeight); 

     //Draw image 
     graphics.DrawImage(bitmap, 0, 0, rect, GraphicsUnit.Pixel); 
    } 

    public AnimateCtl() 
    { 
     //Cache the Graphics object 
     graphics = this.CreateGraphics(); 
     //Instantiate the Timer 
     fTimer = new System.Windows.Forms.Timer(); 
     //Hook up to the Timer's Tick event 
     fTimer.Tick += new System.EventHandler(this.timer1_Tick); 
    } 

    /// <summary> 
    /// Start animation 
    /// </summary> 
    /// <param name="frWidth"></param> 
    /// <param name="DelayInterval"></param> 
    /// <param name="LoopCount"></param> 
    public void StartAnimation(int frWidth, int DelayInterval, int LoopCount) 
    { 

     frameWidth = frWidth; 
     //How many times to loop 
     loopCount = LoopCount; 
     //Reset loop counter 
     loopCounter = 0; 
     //Calculate the frameCount 
     frameCount = bitmap.Width/frameWidth; 
     frameHeight = bitmap.Height; 
     //Resize the control 
     //this.Size(frameWidth, frameHeight); 
     //Assign delay interval to the timer 
     fTimer.Interval = DelayInterval; 
     //Start the timer 
     fTimer.Enabled = true; 
    } 

    private void timer1_Tick(object sender, System.EventArgs e) 
    { 
     if (loopCount == -1) //loop continuously 
     { 
      this.DrawFrame(); 
     } 
     else 
     { 
      if (loopCount == loopCounter) //stop the animation 
       fTimer.Enabled = false; 
      else 
       this.DrawFrame(); 
     } 
    } 

    private void DrawFrame() 
    { 
     if (currentFrame < frameCount - 1) 
     { 
      //move to the next frame 
      currentFrame++; 
     } 
     else 
     { 
      //increment the loopCounter 
      loopCounter++; 
      currentFrame = 0; 
     } 
     Draw(currentFrame); 
    } 

，并在我的Form1中：

public partial class Form1 : Form 
{ 
    AnimateCtl animCtl; 

    public Form1() 
    { 
     InitializeComponent(); 

     //Instantiate control 
     animCtl = new AnimateCtl(); 
     //Assign the Bitmap from the image file 
     animCtl.Bitmap = new Bitmap(@"\Program Files\Animacion\Animacion-Frames.jpg"); 
     //Set the location 
     animCtl.Location = new Point(0, 0); 
     //Add to control to the Form 
     this.Controls.Add(animCtl); 

     animCtl.StartAnimation(240, 100, 3); 
    }   
} 

为什么它不绘制矩形在正确的尺寸？ 感谢您的帮助！

Answer 1

删除抽奖梅索德和更新并条机这样

private void DrawFrame() { 
     if (currentFrame < frameCount - 1) { 
      currentFrame++; 
     } else { 
      loopCounter++; 
      currentFrame = 0; 
     } 
     this.Invalidate(); 
    } 

    protected override void OnPaint(PaintEventArgs e) { 
     base.OnPaint(e); 

     int XLocation = currentFrame * frameWidth; 
     Rectangle rect = new Rectangle(XLocation, 0, frameWidth, frameHeight); 
     e.Graphics.DrawImage(bitmap, 0, 0, rect, GraphicsUnit.Pixel); 
    } 

永远不要使用this.CreateGraphics（）。覆盖OnPaint方法是正确的方法。调用this.Invalidate（）;后，OnPaint将始终触发。

有了this.CreateGraphics（），你只能得到当前的图形大小，但在表单显示控件大小可能已经改变之后。