android drawRect没有画任何东西

概述我碰到了这个基本的drawRect,没有显示任何内容,我也不知道为什么.onDrawprotectedvoidonDraw(Canvascanvas){canvas.drawBitmap(canvasBitmap,0,0,canvasPaint);canvas.drawCircle(circle1x,circle1y,circleRadius,circlePaint);canvas.drawCircle(ci

我碰到了这个基本的drawRect,没有显示任何内容,我也不知道为什么.

onDraw

protected voID onDraw(Canvas canvas) {    canvas.drawBitmap(canvasBitmap, 0, 0, canvasPaint);    canvas.drawCircle(circle1x, circle1y, circleRadius, circlePaint);    canvas.drawCircle(circle2x, circle2y, circleRadius, circlePaint);    canvas.drawRect(rect, rectPaint);}

setupCropPing

在onDraw之前运行,并从VIEw构造函数调用以设置所有var

private voID setupCropPing() {    final float scale = getContext().getResources().getdisplayMetrics().density;    circleRadius = (int) (circleRadiusDp * scale + 0.5f);    displayMetrics metrics = new displayMetrics();    ((Activity) getContext()).getwindowManager().getDefaultdisplay().getMetrics(metrics);    displayX = metrics.wIDthPixels;    displayY = metrics.heightPixels;    cropAreaY = displayY / 3;    cropAreaX = displayX;    //Setting up the circles for adjusting    circle1x = displayX / 2;    circle1y = displayY / 2 - (cropAreaY / 2);    circle2x = displayX / 2;    circle2y = displayY / 2 + (cropAreaY / 2);    canvasPaint = new Paint();    canvasPaint.setcolor(0xffffff00);    circlePaint = new Paint();    circlePaint.setcolor(0xffffff00);    circlePaint.setAntiAlias(true);    rectPaint = new Paint();    rectPaint.setcolor(0xffffff00);    rect = new Rect();    rect.set(0, circle1y, 0, displayY - cropAreaY - circle1y);}

drawCircle可以正常工作并按我的期望进行绘制,我检查了赋予drawRect的数字,并按应有的方式设置了它们,因此我真的不知道这里可能出什么问题.

全视图类

package com.samplersnapshoot.domiq.samplersnapshoot;import androID.app.Activity;import androID.content.Context;import androID.graphics.Bitmap;import androID.graphics.BitmapFactory;import androID.graphics.Canvas;import androID.graphics.Paint;import androID.graphics.PorterDuff;import androID.graphics.Rect;import androID.util.AttributeSet;import androID.util.displayMetrics;import androID.util.Log;import androID.vIEw.VIEw;import java.io.file;import java.io.fileNotFoundException;import java.io.IOException;import java.io.RandomAccessfile;import java.nio.MappedByteBuffer;import java.nio.channels.fileChannel;import java.util.concurrent.CountDownLatch;/** * Created by domix on 14.8.2015.. */public class CropPingVIEw extends VIEw {public final String TAG = "DEBUG";private Canvas cropCanvas;private Bitmap canvasBitmap;private int displayX;private int displayY;private int circle1x = 0;private int circle2x = 0;private int circle1y = 0;private int circle2y = 0;private int circleRadiusDp = 20;private int circleRadius = 100;private int cropAreaX = 0;private int cropAreaY = 0;private Rect rect;private Paint canvasPaint;private Paint circlePaint;private Paint rectPaint;public CropPingVIEw(Context context, AttributeSet attrs){    super(context, attrs);    setupCropPing();}private voID setupCropPing() {    final float scale = getContext().getResources().getdisplayMetrics().density;    circleRadius = (int) (circleRadiusDp * scale + 0.5f);    displayMetrics metrics = new displayMetrics();    ((Activity) getContext()).getwindowManager().getDefaultdisplay().getMetrics(metrics);    displayX = metrics.wIDthPixels;    displayY = metrics.heightPixels;    cropAreaY = displayY / 3;    cropAreaX = displayX;    //Setting up the circles for adjusting    circle1x = displayX / 2;    circle1y = displayY / 2 - (cropAreaY / 2);    circle2x = displayX / 2;    circle2y = displayY / 2 + (cropAreaY / 2);    canvasPaint = new Paint();    canvasPaint.setcolor(0xffffff00);    circlePaint = new Paint();    circlePaint.setcolor(0xffffff00);    circlePaint.setAntiAlias(true);    rectPaint = new Paint();    rectPaint.setARGB(50, 135, 225, 255);}/*@OverrIDeprotected voID onMeasure (int wIDthMeasureSpec, int heightmeasureSpec) {    displayX = wIDthMeasureSpec;    displayY = heightmeasureSpec;    invalIDate();    super.onMeasure(wIDthMeasureSpec, heightmeasureSpec);}*/@OverrIDeprotected voID onSizeChanged(int w, int h, int olDW, int oldh) {    super.onSizeChanged(w, h, olDW, oldh);    //Getting bitmap    getPath myPath = new getPath();    final file myfile = myPath.getLastModifIEdfile();    final CountDownLatch latch = new CountDownLatch(1);    Thread getCanvasBitmap = new Thread() {        public voID run() {            BitmapFactory.Options opt = new BitmapFactory.Options();            opt.inDither = true;            opt.inPreferredConfig = Bitmap.Config.ARGB_8888;            int i = 0;            while (canvasBitmap == null && ++i < 500) {                System.gc();                Log.d(TAG, "Trying again: " + i);                canvasBitmap = BitmapFactory.decodefile(myfile.getabsolutePath(), opt);            }            latch.countDown();        }    };    getCanvasBitmap.start();    try {        latch.await();    } catch (InterruptedException e) {        e.printstacktrace();    }    //Turning into mutable bitmap    myfile.getParentfile().mkdirs();    RandomAccessfile randomAccessfile = null;    try {        randomAccessfile = new RandomAccessfile(myfile, "rw");    } catch (fileNotFoundException e) {        e.printstacktrace();    }    int bWIDth = canvasBitmap.getWIDth();    int bHeight = canvasBitmap.getHeight();    fileChannel channel = randomAccessfile.getChannel();    MappedByteBuffer map = null;    try {        map = channel.map(fileChannel.MapMode.READ_WRITE, 0, bWIDth*bHeight*4);    } catch (IOException e) {        e.printstacktrace();    }    canvasBitmap.copyPixelsToBuffer(map);    canvasBitmap.recycle();    this.canvasBitmap = Bitmap.createBitmap(bWIDth, bHeight, Bitmap.Config.ARGB_8888);    map.position(0);    this.canvasBitmap.copyPixelsFromBuffer(map);    try {        channel.close();    } catch (IOException e) {        e.printstacktrace();    }    try {        randomAccessfile.close();    } catch (IOException e) {        e.printstacktrace();    }}protected voID onDraw(Canvas canvas) {    canvas.drawBitmap(canvasBitmap, 0, 0, canvasPaint);    Log.d(TAG, "display vars:" + displayX + " " + displayY);    canvas.drawCircle(circle1x, circle1y, circleRadius, circlePaint);    canvas.drawCircle(circle2x, circle2y, circleRadius, circlePaint);    rect = new Rect();    rect.set(5, circle1y, displayX, displayY - cropAreaY - circle1y);    canvas.drawRect(rect, rectPaint);}}

该类的代码编写得还很差,我还没有集成很多功能并对其进行清理.

解决方法:

rect.set(0, circle1y, 0, displayY - cropAreaY - circle1y);

您的左坐标和右坐标均为0.

它的

rect.set(int left, int top, int right, int bottom);

编辑：

好吧,我设法查明了这个问题.以下行在您的VIEw类中

rect.set(5, circle1y, displayX, displayY - cropAreaY - circle1y);

在您的代码中使用相同的计算,对于具有480×800显示屏的设备,我得到以下坐标值.

rect.set(5, 267, 480, 267);

同样,您的Rect侧面重叠；您的顶侧和底侧都在相同的Y坐标上.这将产生一个262像素宽和零高度的矩形.

您需要做的就是更新坐标计算并提供适当的坐标.否则,您的Rect应该画的很好.

总结

以上是内存溢出为你收集整理的android drawRect没有画任何东西全部内容，希望文章能够帮你解决android drawRect没有画任何东西所遇到的程序开发问题。

如果觉得内存溢出网站内容还不错，欢迎将内存溢出网站推荐给程序员好友。