無法使用畫布創建位圖

Question

您介意幫我解決這個問題嗎？

我想繪製一個圓形的位圖，然後將位圖繪製到mapView。 但位圖仍未創建。 這裏是我的代碼：

public class CustomOverlay extends Overlay { 
    public HeatPoint pt; 
    Context mContext; 
    Bitmap bmp; 
    public CustomOverlay(HeatPoint pt,Context context){ 
     this.pt=pt; 
     this.mContext = context; 
     bmp = Bitmap.createBitmap(200, 200, Bitmap.Config.ARGB_8888); 
     Paint gp = new Paint(); 

    gp.setColor(0xFF0000); 

    gp.setStyle(Style.FILL); 
    Canvas myCanvas = new Canvas(bmp); 
    myCanvas.drawRect(10,10,40,40,gp); 

    } 

    @Override 
    public boolean draw(Canvas canvas, MapView mapView, 
    boolean shadow, long when) 
    { 
     super.draw(canvas, mapView, shadow);     

     Point screenPts = new Point(); 
     mapView.getProjection().toPixels(pt.getGeo(), screenPts); 
     canvas.drawBitmap(bmp, screenPts.x-16, screenPts.y-2, null); 
     return true; 
    }  

} 

在這段代碼中，我想在屏幕上繪製一個圓，但是當我運行它，什麼都沒有發生。 感謝您的幫助。

Answer 1

你可以看到下面的代碼

int w = WIDTH_PX, h = HEIGHT_PX; 

BitmapConfig conf = Bitmap.Config.ARGB_8888; // see other conf types 
Bitmap bmp = Bitmap.createBitmap(w, h, conf); // this creates a MUTABLE bitmap 
Canvas canvas = new Canvas(bmp); 

本教程可以幫助你

http://www.tutorialforandroid.com/2010/11/drawing-with-canvas-in-android-renewed.html