自定义View——画板

今天实现的是画板效果

实现原理

根据触摸事件返回的坐标点绘制path路径

 @Override public boolean onTouchEvent(MotionEvent event) { x = event.getX(); y = event.getY(); switch (event.getAction()) { case MotionEvent.ACTION_DOWN: //当触摸屏幕的时候将点移动到触摸的位置 path.moveTo(x, y); break; case MotionEvent.ACTION_MOVE: //当滑动的时候将滑动路径连接起来 path.lineTo(x, y); //在滑动的过程中不断更新界面 invalidate(); break; case MotionEvent.ACTION_UP: //当手抬起的时候更新界面 invalidate(); break; } return true; } 

canvas绘制路径

//绘制白色背景 canvas.drawColor(Color.WHITE); //绘制路径 canvas.drawPath(path, paint); 

最后保存自己绘制的图像

 public void save() { setDrawingCacheEnabled(false); setDrawingCacheEnabled(true); new Thread(new Runnable() { @Override public void run() { Bitmap drawingCache = getDrawingCache(true); File file = new File(getContext().getCacheDir() + "123.png"); FileOutputStream fileOutputStream = null; try { fileOutputStream = new FileOutputStream(file); drawingCache.compress(Bitmap.CompressFormat.PNG, 100, fileOutputStream); fileOutputStream.flush(); } catch (Exception e) { e.printStackTrace(); } finally { if (fileOutputStream != null) { try { fileOutputStream.close(); try { MediaStore.Images.Media.insertImage(getContext().getContentResolver(), file.getAbsolutePath(), "sad.png", null); } catch (FileNotFoundException e) { e.printStackTrace(); } // 最后通知图库更新 getContext().sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.parse("file://" + file.getPath()))); Log.e("测试", "保存成功"); } catch (IOException e) { e.printStackTrace(); } } } } }).start(); } 

完整代码

package com.yuyigufen.customview; import android.content.Context; import android.content.Intent; import android.graphics.Bitmap; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.graphics.Path; import android.net.Uri; import android.provider.MediaStore; import android.support.annotation.Nullable; import android.util.AttributeSet; import android.util.Log; import android.view.MotionEvent; import android.view.View; import java.io.File; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.util.Random; /** * Created by Administrator on 2018/6/11 0011. */ public class MyPaintView extends View { private float x; private float y; private Path path; private Paint paint; private Random random; public MyPaintView(Context context) { super(context); } public MyPaintView(Context context, @Nullable AttributeSet attrs) { super(context, attrs); init(); } private void init() { random = new Random(); paint = new Paint(Paint.ANTI_ALIAS_FLAG); paint.setStyle(Paint.Style.STROKE); paint.setStrokeWidth(10); paint.setColor(Color.RED); path = new Path(); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { setMeasuredDimension(measureSize(widthMeasureSpec), measureSize(heightMeasureSpec)); } private int measureSize(int size) { int mode = MeasureSpec.getMode(size); int s = MeasureSpec.getSize(size); if (mode == MeasureSpec.EXACTLY) { return s; } else if (mode == MeasureSpec.AT_MOST) { return Math.min(s, 200); } else { return 200; } } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); canvas.drawColor(Color.WHITE); canvas.drawPath(path, paint); } @Override public boolean onTouchEvent(MotionEvent event) { x = event.getX(); y = event.getY(); switch (event.getAction()) { case MotionEvent.ACTION_DOWN: path.moveTo(x, y); break; case MotionEvent.ACTION_MOVE: path.lineTo(x, y); invalidate(); break; case MotionEvent.ACTION_UP: invalidate(); break; } return true; } public void clear() { path.reset(); invalidate(); } public void save() { setDrawingCacheEnabled(false); setDrawingCacheEnabled(true); new Thread(new Runnable() { @Override public void run() { Bitmap drawingCache = getDrawingCache(true); File file = new File(getContext().getCacheDir() + "123.png"); FileOutputStream fileOutputStream = null; try { fileOutputStream = new FileOutputStream(file); drawingCache.compress(Bitmap.CompressFormat.PNG, 100, fileOutputStream); fileOutputStream.flush(); } catch (Exception e) { e.printStackTrace(); } finally { if (fileOutputStream != null) { try { fileOutputStream.close(); try { MediaStore.Images.Media.insertImage(getContext().getContentResolver(), file.getAbsolutePath(), "sad.png", null); } catch (FileNotFoundException e) { e.printStackTrace(); } // 最后通知图库更新 getContext().sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.parse("file://" + file.getPath()))); Log.e("测试", "保存成功"); } catch (IOException e) { e.printStackTrace(); } } } } }).start(); } } 

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