Android Canvas à Bitmap

Question

J'ai été la recherche en ligne sur la façon de transformer ce qui est sur une toile en un bitmap. J'ai essayé plusieurs façons de le faire comme enregistrer le cache de dessin sur une image bitmap, mais le résultat final est le bitmap d'arrière-plan clignotant pendant un moment, puis devenant un écran noir. L'image de test est affichée sur l'arrière-plan, mais ne se superpose pas à l'arrière-plan de l'appel suivant de OnDraw.

MainThreading{ 

         ... 

       if(notuptodate == true){ 

         //call readyBackground to create the background bitmap 
         this.mainPanel.readyBackground(canvas); 
         //post the canvas 
         surfaceHolder.unlockCanvasAndPost(canvas); 
         //clean the Canvas 
         canvas = null; 
         //ready new Canvas 
         canvas = this.surfaceHolder.lockCanvas();//lock the canvas to enable editing 






        }//if not true 

        if (MainThreading.notuptodate == false){ 

         mainPanel.onDraw(canvas); 


        }//if false 
... 
       }//mainthreading 

    //this method is run first to create the Bitmap that on draw will use 
    public void readyBackGround(Canvas canvas){ 


     if (MainThreading.notuptodate){ 
      //method used to draw multiple Bitmaps onto the canvas 
      renderBackground(canvas); 

      //private Bitmap, this is the supposed proper size of the bitmap 
      backgroundBitmap=Bitmap.createBitmap(240, 320, Config.ARGB_8888); 


      //set the canvas to turn whats on its self onto the bitmap. 
      canvas.setBitmap(backgroundBitmap); 

      //set boolean flag to false so renderBackground won't be called 
      //untill it needs to be updated again 
      MainThreading.notUpToDate = false; 

     } 

     //this method is called when notUpToDate = true 
     @Override 
    protected void onDraw(Canvas canvas){ 


     if (this.threado.getBackground() != null){ 
      canvas.drawBitmap(backgroundBitmap, 0, 0, null); 

      } 

      //this if statement is never activated 
      if (this.threado.getBackground() == null){ 
       Log.d("background nonexistant", "Importante!"); 
      } 
      //draw test object onto background 
      test.DrawObject(canvas); 

       //when MainThreading.notUpToDate = true isn't commented out, the 
       //screen consistantly shows the background, but the test object isn't 
       //drawn 

     //MainThreading.notUpToDate = true; 





     } 

Answer 1

Essayez cette façon ...

- Créer une bitmap de la taille correcte à l'aide Bitmap.createBitmap()

- Créer un canvas instance pointant que ce bitmap à l'aide Canvas(Bitmap) constructeur

- Dessiner à le canvas

- Utilisez le bitmap

Answer 2

public class CanvasToBitmap extends View { 

    Paint paint = new Paint(); 
    Rect mRect = new Rect(); 
    Bitmap bitmap = Bitmap.createBitmap(200, 200, Bitmap.Config.ARGB_8888); 

    public myCanvas(Context context) { 
     super(context); 
     Canvas canvas = new Canvas(bitmap); 
     draw(canvas); 
    } 

    @Override 
    public void onDraw(Canvas canvas) { 

     mRect.set(0, 0, 200, 200); 
     paint.setColor(Color.GREEN); 
     paint.setStyle(Paint.Style.FILL); 
     canvas.drawRect(mRect, paint); 
     canvas.setBitmap(bitmap); 

     ByteArrayOutputStream mByteArrayOutputStream = new ByteArrayOutputStream(); 
     try{ 
      bitmap.compress(Bitmap.CompressFormat.PNG, 100, mByteArrayOutputStream); 

      bitmap = BitmapFactory.decodeStream(new ByteArrayInputStream(mByteArrayOutputStream.toByteArray())); 
      mByteArrayOutputStream.flush(); 
      mByteArrayOutputStream.close(); 
     } catch (Exception e) {e.printStackTrace();} 
    } 
} 

Créer une nouvelle instance:

CanvasToBitmap canvasToBitmap = new CanvasToBitmap(getBaseContext()); 

Get bitmap de canvasToBitmap:

Bitmap bitmap = canvasToBitmap.bitmap;