In einigen Fällen auf Android

Question

Distorting eines Bildes zu einem Viereck scheitern Ich verwende Matrix.setPolyToPoly Funktion, um eine ausgewählte Region (4 Ecken) einer Bitmap in ein Rechteck zu transformieren und normalerweise funktioniert es erstaunlich. Aber im nächsten Beispiel:

Die polyToPoly Funktion schlägt die perspektivische Transformation:

ich gezeichnet haben zwei Linien für die Prüfung, markieren Sie die Zeilen, in denen ich die vier ausgewählten Punkten wollen .

Was mache ich falsch? Vielen Dank!

EDIT: Ich habe das Problem mit canvas.drawBitmapMesh gelöst haben, Dank pskink für Ihre Beratung !!

Dies ist der letzte Code

private float[] generateVertices(int widthBitmap, int heightBitmap) { 
    float[] vertices=new float[(WIDTH_BLOCK+1)*(HEIGHT_BLOCK+1)*2]; 

    float widthBlock = (float)widthBitmap/WIDTH_BLOCK; 
    float heightBlock = (float)heightBitmap/HEIGHT_BLOCK; 

    for(int i=0;i<=HEIGHT_BLOCK;i++) 
     for(int j=0;j<=WIDTH_BLOCK;j++) { 
      vertices[i * ((HEIGHT_BLOCK+1)*2) + (j*2)] = j * widthBlock; 
      vertices[i * ((HEIGHT_BLOCK+1)*2) + (j*2)+1] = i * heightBlock; 
     } 
    return vertices; 
} 

private Bitmap perspectiveTransformation(Bitmap bitmap, ArrayList<Point> bitmapPoints) { 

    Bitmap correctedBitmap; 
    int maxX = (int) Math.max(Math.abs(bitmapPoints.get(0).x - bitmapPoints.get(1).x), Math.abs(bitmapPoints.get(2).x - bitmapPoints.get(3).x)); 
    int maxY = (int) Math.max(Math.abs(bitmapPoints.get(0).y - bitmapPoints.get(3).y), Math.abs(bitmapPoints.get(1).y - bitmapPoints.get(2).y)); 
    Log.d("max", "x=" + maxX + " y=" + maxY); //This is the desired final size 

    Bitmap.Config conf = Bitmap.Config.ARGB_8888; 
    correctedBitmap = Bitmap.createBitmap(maxX,maxY,conf); //the final bitmap 
    float mVertices[] =generateVertices(bitmap.getWidth(),bitmap.getHeight()); 

    Point mLeftTop = bitmapPoints.get(0); 
    Point mRightTop = bitmapPoints.get(1); 
    Point mLeftBot = bitmapPoints.get(3); 
    Point mRightBot = bitmapPoints.get(2); //the points on the image where the user has clicked 

    Canvas canvas = new Canvas(correctedBitmap); 

    Matrix matrix = new Matrix(); 
    matrix.setPolyToPoly(
      new float[]{mLeftTop.x, mLeftTop.y, 
        mRightTop.x, mRightTop.y, 
        mRightBot.x, mRightBot.y, 
        mLeftBot.x, mLeftBot.y //the user's points 
      }, 
      0, 
      new float[]{0, 0, 
        maxX - 1, 0, 
        maxX - 1, maxY - 1, 
        0, maxY - 1    //where I want the user points in the corrected image 
      } 
      , 0, 4); 

    canvas.concat(matrix); 

    Paint paint = new Paint(); 
    paint.setAntiAlias(true);  //testing parameters 
    paint.setFilterBitmap(true); //testing parameters 

    paint.setColor(Color.BLUE); 
    paint.setStyle(Paint.Style.STROKE); 

    canvas.drawBitmapMesh(bitmap, WIDTH_BLOCK , HEIGHT_BLOCK, mVertices,0,null,0, paint); //draw the original bitmap into the corrected bitmap with PolyToPoly transformation matrix 

    canvas.drawLine(mLeftTop.x, mLeftTop.y, mRightBot.x, mRightBot.y, paint); //draw two lines for testing the transformation matrix 
    canvas.drawLine(mLeftBot.x, mLeftBot.y, mRightTop.x, mRightTop.y, paint); 

    //bitmap.recycle(); //just testing 

    return correctedBitmap; 
} 

Answer 1

private float[] generateVertices(int widthBitmap, int heightBitmap) { 
    float[] vertices=new float[(WIDTH_BLOCK+1)*(HEIGHT_BLOCK+1)*2]; 

    float widthBlock = (float)widthBitmap/WIDTH_BLOCK; 
    float heightBlock = (float)heightBitmap/HEIGHT_BLOCK; 

    for(int i=0;i<=HEIGHT_BLOCK;i++) 
     for(int j=0;j<=WIDTH_BLOCK;j++) { 
      vertices[i * ((HEIGHT_BLOCK+1)*2) + (j*2)] = j * widthBlock; 
      vertices[i * ((HEIGHT_BLOCK+1)*2) + (j*2)+1] = i * heightBlock; 
     } 
    return vertices; 
} 

private Bitmap perspectiveTransformation(Bitmap bitmap, ArrayList<Point> bitmapPoints) { 

    Bitmap correctedBitmap; 
    int maxX = (int) Math.max(Math.abs(bitmapPoints.get(0).x - bitmapPoints.get(1).x), Math.abs(bitmapPoints.get(2).x - bitmapPoints.get(3).x)); 
    int maxY = (int) Math.max(Math.abs(bitmapPoints.get(0).y - bitmapPoints.get(3).y), Math.abs(bitmapPoints.get(1).y - bitmapPoints.get(2).y)); 
    Log.d("max", "x=" + maxX + " y=" + maxY); //This is the desired final size 

    Bitmap.Config conf = Bitmap.Config.ARGB_8888; 
    correctedBitmap = Bitmap.createBitmap(maxX,maxY,conf); //the final bitmap 
    float mVertices[] =generateVertices(bitmap.getWidth(),bitmap.getHeight()); 

    Point mLeftTop = bitmapPoints.get(0); 
    Point mRightTop = bitmapPoints.get(1); 
    Point mLeftBot = bitmapPoints.get(3); 
    Point mRightBot = bitmapPoints.get(2); //the points on the image where the user has clicked 

    Canvas canvas = new Canvas(correctedBitmap); 

    Matrix matrix = new Matrix(); 
    matrix.setPolyToPoly(
      new float[]{mLeftTop.x, mLeftTop.y, 
        mRightTop.x, mRightTop.y, 
        mRightBot.x, mRightBot.y, 
        mLeftBot.x, mLeftBot.y //the user's points 
      }, 
      0, 
      new float[]{0, 0, 
        maxX - 1, 0, 
        maxX - 1, maxY - 1, 
        0, maxY - 1    //where I want the user points in the corrected image 
      } 
      , 0, 4); 

    canvas.concat(matrix); 

    Paint paint = new Paint(); 
    paint.setAntiAlias(true);  //testing parameters 
    paint.setFilterBitmap(true); //testing parameters 

    paint.setColor(Color.BLUE); 
    paint.setStyle(Paint.Style.STROKE); 

    canvas.drawBitmapMesh(bitmap, WIDTH_BLOCK , HEIGHT_BLOCK, mVertices,0,null,0, paint); //draw the original bitmap into the corrected bitmap with PolyToPoly transformation matrix 

    canvas.drawLine(mLeftTop.x, mLeftTop.y, mRightBot.x, mRightBot.y, paint); //draw two lines for testing the transformation matrix 
    canvas.drawLine(mLeftBot.x, mLeftBot.y, mRightTop.x, mRightTop.y, paint); 

    //bitmap.recycle(); //just testing 

    return correctedBitmap; 
}