在活动中绘制图像的最佳方式

Question

我需要绘制位图并在活动类上按下按钮时进行更改。我曾尝试使用View类，但不幸的是我没有运气。我认为这将是一个简单的任务。

有没有人有如何做到这一点的想法？我一直在为此奋斗了2天，似乎没有任何体面的解决方案。

活动课

public class PhonicsActivity extends Activity{ 

int letterStatus = 0; 

protected void onCreate (Bundle savedInstanceState){ 

    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity1_phonics); 

    final Intent phonicsBackIntent = new Intent(this, PhonicsMenu.class); 

    final Button nextButton = (Button) findViewById(R.id.nextbutton); 
    final Button backButton = (Button) findViewById(R.id.backbutton); 
    final Button menuButton = (Button) findViewById(R.id.menubutton); 

    nextButton.setOnClickListener(new View.OnClickListener() { 

     @Override 
     public void onClick(View v) { 

     } 
    }); 

视图类

public class PhonicsView extends View { 

private int letterStatus = 1; 

public PhonicsView(Context context) { 
    super(context); 
    // TODO Auto-generated constructor stub 
} 

public PhonicsView(Context context, AttributeSet attrs) { 
    super(context, attrs); 
    // TODO Auto-generated constructor stub 
    init(); 
} 

public PhonicsView(Context context, AttributeSet attrs, int defStyle) { 
    super(context, attrs, defStyle); 
    // TODO Auto-generated constructor stub 
    init(); 
} 

private void init(){ 


    } 


protected void onDraw(Canvas canvas) { 

    drawLetterA(canvas); 

    if (letterStatus == 2){ 

     Bitmap myBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.lettera); 
     canvas.drawBitmap(myBitmap, 0, 0, null); 

    } 

} 

我需要的按钮在活动覆盖前面的图像或清除画布，然后绘制下一个字母。

Answer 1

这是谷歌一个fingerpaint尝试开始的东西和自定义它找出您的问题

public class FingerPaint extends GraphicsActivity 
     implements ColorPickerDialog.OnColorChangedListener { 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(new MyView(this)); 

     mPaint = new Paint(); 
     mPaint.setAntiAlias(true); 
     mPaint.setDither(true); 
     mPaint.setColor(0xFFFF0000); 
     mPaint.setStyle(Paint.Style.STROKE); 
     mPaint.setStrokeJoin(Paint.Join.ROUND); 
     mPaint.setStrokeCap(Paint.Cap.ROUND); 
     mPaint.setStrokeWidth(12); 

     mEmboss = new EmbossMaskFilter(new float[] { 1, 1, 1 }, 
             0.4f, 6, 3.5f); 

     mBlur = new BlurMaskFilter(8, BlurMaskFilter.Blur.NORMAL); 
    } 

    private Paint  mPaint; 
    private MaskFilter mEmboss; 
    private MaskFilter mBlur; 

    public void colorChanged(int color) { 
     mPaint.setColor(color); 
    } 

    public class MyView extends View { 

     private static final float MINP = 0.25f; 
     private static final float MAXP = 0.75f; 

     private Bitmap mBitmap; 
     private Canvas mCanvas; 
     private Path mPath; 
     private Paint mBitmapPaint; 

     public MyView(Context c) { 
      super(c); 

      mPath = new Path(); 
      mBitmapPaint = new Paint(Paint.DITHER_FLAG); 
     } 

     @Override 
     protected void onSizeChanged(int w, int h, int oldw, int oldh) { 
      super.onSizeChanged(w, h, oldw, oldh); 
      mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888); 
      mCanvas = new Canvas(mBitmap); 
     } 

     @Override 
     protected void onDraw(Canvas canvas) { 
      canvas.drawColor(0xFFAAAAAA); 

      canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint); 

      canvas.drawPath(mPath, mPaint); 
     } 

     private float mX, mY; 
     private static final float TOUCH_TOLERANCE = 4; 

     private void touch_start(float x, float y) { 
      mPath.reset(); 
      mPath.moveTo(x, y); 
      mX = x; 
      mY = y; 
     } 
     private void touch_move(float x, float y) { 
      float dx = Math.abs(x - mX); 
      float dy = Math.abs(y - mY); 
      if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) { 
       mPath.quadTo(mX, mY, (x + mX)/2, (y + mY)/2); 
       mX = x; 
       mY = y; 
      } 
     } 
     private void touch_up() { 
      mPath.lineTo(mX, mY); 
      // commit the path to our offscreen 
      mCanvas.drawPath(mPath, mPaint); 
      // kill this so we don't double draw 
      mPath.reset(); 
     } 

     @Override 
     public boolean onTouchEvent(MotionEvent event) { 
      float x = event.getX(); 
      float y = event.getY(); 

      switch (event.getAction()) { 
       case MotionEvent.ACTION_DOWN: 
        touch_start(x, y); 
        invalidate(); 
        break; 
       case MotionEvent.ACTION_MOVE: 
        touch_move(x, y); 
        invalidate(); 
        break; 
       case MotionEvent.ACTION_UP: 
        touch_up(); 
        invalidate(); 
        break; 
      } 
      return true; 
     } 
    } 

    private static final int COLOR_MENU_ID = Menu.FIRST; 
    private static final int EMBOSS_MENU_ID = Menu.FIRST + 1; 
    private static final int BLUR_MENU_ID = Menu.FIRST + 2; 
    private static final int ERASE_MENU_ID = Menu.FIRST + 3; 
    private static final int SRCATOP_MENU_ID = Menu.FIRST + 4; 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     super.onCreateOptionsMenu(menu); 

     menu.add(0, COLOR_MENU_ID, 0, "Color").setShortcut('3', 'c'); 
     menu.add(0, EMBOSS_MENU_ID, 0, "Emboss").setShortcut('4', 's'); 
     menu.add(0, BLUR_MENU_ID, 0, "Blur").setShortcut('5', 'z'); 
     menu.add(0, ERASE_MENU_ID, 0, "Erase").setShortcut('5', 'z'); 
     menu.add(0, SRCATOP_MENU_ID, 0, "SrcATop").setShortcut('5', 'z'); 

     /**** Is this the mechanism to extend with filter effects? 
     Intent intent = new Intent(null, getIntent().getData()); 
     intent.addCategory(Intent.CATEGORY_ALTERNATIVE); 
     menu.addIntentOptions(
           Menu.ALTERNATIVE, 0, 
           new ComponentName(this, NotesList.class), 
           null, intent, 0, null); 
     *****/ 
     return true; 
    } 

    @Override 
    public boolean onPrepareOptionsMenu(Menu menu) { 
     super.onPrepareOptionsMenu(menu); 
     return true; 
    } 

    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 
     mPaint.setXfermode(null); 
     mPaint.setAlpha(0xFF); 

     switch (item.getItemId()) { 
      case COLOR_MENU_ID: 
       new ColorPickerDialog(this, this, mPaint.getColor()).show(); 
       return true; 
      case EMBOSS_MENU_ID: 
       if (mPaint.getMaskFilter() != mEmboss) { 
        mPaint.setMaskFilter(mEmboss); 
       } else { 
        mPaint.setMaskFilter(null); 
       } 
       return true; 
      case BLUR_MENU_ID: 
       if (mPaint.getMaskFilter() != mBlur) { 
        mPaint.setMaskFilter(mBlur); 
       } else { 
        mPaint.setMaskFilter(null); 
       } 
       return true; 
      case ERASE_MENU_ID: 
       mPaint.setXfermode(new PorterDuffXfermode(
                 PorterDuff.Mode.CLEAR)); 
       return true; 
      case SRCATOP_MENU_ID: 
       mPaint.setXfermode(new PorterDuffXfermode(
                PorterDuff.Mode.SRC_ATOP)); 
       mPaint.setAlpha(0x80); 
       return true; 
     } 
     return super.onOptionsItemSelected(item); 
    } 
}