Question

在Android应用程序中，我试图截取一个名为Sierpinski Triangle的视图。但是，位图始终返回null。 Sierpinski Triangle只有onDraw方法的图形（没有按钮，textviews，背景......）这是我的代码：

        sierpinskiTriangle.setDrawingCacheEnabled(true);
        sierpinskiTriangle.buildDrawingCache(true);
        sierpinskiTriangle.setDrawingCacheQuality(2);
        sierpinskiTriangle.measure(MeasureSpec.makeMeasureSpec(50, MeasureSpec.UNSPECIFIED), 
        MeasureSpec.makeMeasureSpec(50, MeasureSpec.UNSPECIFIED));
        sierpinskiTriangle.layout(0, 0, sierpinskiTriangle.getMeasuredWidth(), sierpinskiTriangle.getMeasuredHeight());
        Bitmap screensaver =sierpinskiTriangle.getDrawingCache(true);
        Bitmap screenshot = Bitmap.createBitmap(this.sierpinskiTriangle.getWidth(), this.sierpinskiTriangle.getHeight(), Config.ARGB_8888);

请帮助，我已经在这几个小时了。

以下是Sierpinski Triangle的代码：

package com.Marco.Fractal;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Bitmap.Config;
import android.graphics.drawable.ShapeDrawable;
import android.graphics.drawable.shapes.RectShape;
import android.view.View;

public class SierpinskiTriangle extends View{


Paint paint = new Paint();
int stage;
int width;
int height;
int h1, h2, w1, w2,w3;

public SierpinskiTriangle(Context context, int t, int s, int w, int h) {
super(context);
stage = s;
width=w;
height=h;
paint.setColor(Color.RED);
h1=(int)(height/2-((((width-30)/4)*1.732)));
h2=(int)(height/2+((((width-30)/4)*1.732)));
w1=15;
w2=width-15;
w3=width/2;
}

protected void onDraw(final Canvas canvas) {

    this.setDrawingCacheEnabled(true);
    this.buildDrawingCache(true);
    canvas.drawLine(w1, h2, w3, (float) h1, paint);
    canvas.drawLine(w2, h2, w3, (float) h1, paint);
    canvas.drawLine(w1, h2, w2, h2, paint);
    triangles(canvas, w1, h2, w3, h1, w2, h2, stage);



}
protected void triangles(final Canvas canvas, int x1, int y1, int x2, int y2, int x3, int y3, int r)
{
    if(r==0)
    {
        canvas.drawLine(x1, y1, x2, y2, paint);
        canvas.drawLine(x2, y2, x3, y3, paint);
        canvas.drawLine(x3, y3, x1, y1, paint);
    }
    else
    {
        int xm1 = (x1+x2)/2;
        int xm2 = (x2+x3)/2;
        int xm3 = (x1+x3)/2;
        int ym1 = (y1+y2)/2;
        int ym2 = (y2+y3)/2;
        int ym3 = (y1+y3)/2;
        triangles(canvas, x1, y1, xm1, ym1, xm3,ym3, r-1);
        triangles(canvas, xm3, ym3,xm2, ym2, x3, y3, r-1);
        triangles(canvas, xm1, ym1, x2,y2, xm2,ym2,r-1);
    }
}

}

Answer 1

<强> [EDIT2]

我感觉你的onDraw方法中的以下两行让你搞砸了：

this.setDrawingCacheEnabled(true);     
this.buildDrawingCache(true);

尝试删除它们，看看会发生什么!!!

<强> [EDIT1] 尝试从简单的所有内容中简化代码：

Bitmap screenshot;
sierpinskiTriangle.setDrawingCacheEnabled(true);
screenshot = Bitmap.createBitmap(sierpinskiTriangle.getDrawingCache(true));
sierpinskiTriangle.setDrawingCacheEnabled(false);

<强> [原稿]

尝试：

Bitmap screenshot = Bitmap.createBitmap(sierpinskiTriangle.getDrawingCache(true));

另见：

How to programmatically take a screenshot in Android?

Answer 2

感谢您购买所有帮助，我终于解决了问题。

我将此代码添加到sierpinski triangle：

   public Bitmap getBitmap()
    {
        Bitmap b = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        Canvas c = new Canvas(b);
        draw(c);
        return b;
    }

这会截取屏幕截图，但会在屏幕截图时放大。如果我找到解决此问题的方法，我会发布

View的屏幕截图始终为null。 Android的

2 个答案: