以下为自定义View，继承自ImageView，可实现对图片进行编辑，包括普通涂鸦、画圆、画矩形、画箭头以及写字。
并且，可以对线条大小、线条颜色、字体大小、字体颜色进行设置。另外，实现了文字自动换行、移动文字位置、撤销等功能。
主要用到了Canvas、Paint、TextPaint、StaticLayout等Android中的图形图像方面和自定义View的技术。
下面直接上代码：
package .joincc.secusoft.view;import android.content.Context;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.graphics.Path;import android.graphics.RectF;import android.os.Environment;import android.os.Handler;import android.os.Message;import android.text.DynamicLayout;import android.text.Layout;import android.text.StaticLayout;import android.text.TextPaint;import android.util.AttributeSet;import android.util.DisplayMetrics;import android.util.Log;import android.view.MotionEvent;import android.widget.ImageView;import java.io.FileOutputStream;import java.io.IOException;import .joincc.secusoft.R;/*** Created by Administrator on /9/4.* 自定义View.使用Canvas、Paint等来实现图片编辑功能（包括普通涂鸦、画圆、画矩形、画箭头、写字）*/public class GraffitiView extends ImageView {private Paint paint; //画笔private Bitmap originalBitmap; //源图private Bitmap newBitmap;private Bitmap finalBitmap; //最终保存时的图片private Bitmap finalOvalBitmap;private Bitmap finalRectBitmap;private Bitmap finalArrowBitmap;private Bitmap finalTextBitmap;private float clickX = 0; //触摸时的x坐标private float clickY = 0; //触摸时的y坐标private float startX = 0; //每次绘制起点的x坐标private float startY = 0; //每次绘制起点的y坐标private boolean isEdit = false; //是否允许对图片进行编辑private boolean isMove = true; //是否进行绘制private boolean isClear = false; //是否进行清空private int drawType = 0; //绘制类型：0---线条；1---圆；2---矩形；3---箭头；4---文字private String text;private int color = Color.RED; //画笔颜色private float strokeWidth = 4.0f; //涂鸦线条的宽度private int textSize = 18; //字体大小private int textColor = getResources().getColor(R.color.red); //文字颜色private int mScreenWidth;private int mScreenHeight;private String filePath;public GraffitiView(Context context, AttributeSet attrs) {super(context, attrs);}public void setFilePath(String filePath) {this.filePath = filePath;//根据原位图的大小创建一个新位图，得到的位图是可变的DisplayMetrics dm = getResources().getDisplayMetrics();mScreenWidth = dm.widthPixels;mScreenHeight = dm.heightPixels;originalBitmap = BitmapFactory.decodeFile(filePath).copy(Bitmap.Config.ARGB_8888, true);// new1Bitmap = Bitmap.createBitmap(originalBitmap); //得到一个不可变位图finalBitmap = Bitmap.createScaledBitmap(originalBitmap, mScreenWidth, mScreenHeight, true);invalidate();}@Overrideprotected void onDraw(Canvas canvas) {super.onDraw(canvas);switch (drawType) {case 0:canvas.drawBitmap(handWriting(), 0, 0, null);break;case 1:canvas.drawBitmap(drawOval(), 0, 0, null);break;case 2:canvas.drawBitmap(drawRect(), 0, 0, null);break;case 3:canvas.drawBitmap(drawArrow(), 0, 0, null);break;case 4:canvas.drawBitmap(writeText(), 0, 0, null);break;}}/*** 画线条* @return*/public Bitmap handWriting() {if (isClear) {isClear = false;finalBitmap = newBitmap;return finalBitmap;} else {Bitmap bitmap = Bitmap.createScaledBitmap(finalBitmap, mScreenWidth, mScreenHeight, true);Canvas canvas = new Canvas(bitmap);paint = new Paint();paint.setStyle(Paint.Style.STROKE);paint.setAntiAlias(true);paint.setColor(color);paint.setStrokeWidth(strokeWidth);if (isMove) { //当移动时绘制canvas.drawLine(startX, startY, clickX, clickY, paint); //在画布上画线（通过起点、终点和画笔）}//起点需要不断变化，否则画出来的不是线而是面，因为起点一直不变startX = clickX;startY = clickY;finalBitmap = bitmap;return finalBitmap;}}/*** 画椭圆（包括圆，圆是一种特殊的椭圆）* @return*/public Bitmap drawOval() {if (isClear) {isClear = false;finalBitmap = newBitmap;return finalBitmap;} else {Bitmap bitmap = Bitmap.createScaledBitmap(finalBitmap, mScreenWidth, mScreenHeight, true);Canvas canvas = new Canvas(bitmap);paint = new Paint();paint.setStyle(Paint.Style.STROKE);paint.setAntiAlias(true);paint.setColor(color);paint.setStrokeWidth(strokeWidth);if (isMove) {canvas.drawOval(new RectF(startX, startY, clickX, clickY), paint);}finalOvalBitmap = bitmap;return finalOvalBitmap;}}/*** 画矩形* @return*/public Bitmap drawRect() {if (isClear) {isClear = false;finalBitmap = newBitmap;return finalBitmap;} else {Bitmap bitmap = Bitmap.createScaledBitmap(finalBitmap, mScreenWidth, mScreenHeight, true);Canvas canvas = new Canvas(bitmap);paint = new Paint();paint.setStyle(Paint.Style.STROKE);paint.setAntiAlias(true);paint.setColor(color);paint.setStrokeWidth(strokeWidth);if (isMove) {canvas.drawRect(startX, startY, clickX, clickY, paint);}finalRectBitmap = bitmap;return finalRectBitmap;}}/*** 画箭头*/public Bitmap drawArrow() {if (isClear) {isClear = false;finalBitmap = newBitmap;return finalBitmap;} else {Bitmap bitmap = Bitmap.createScaledBitmap(finalBitmap, mScreenWidth, mScreenHeight, true);Canvas canvas = new Canvas(bitmap);paint = new Paint();paint.setStyle(Paint.Style.STROKE);paint.setAntiAlias(true);paint.setColor(color);paint.setStrokeWidth(strokeWidth);if (isMove) {drawArrow(startX, startY, clickX, clickY, canvas, paint);}finalArrowBitmap = bitmap;return finalArrowBitmap;}}public void drawArrow(float startX, float startY, float endX, float endY, Canvas canvas, Paint paint) {double H = 10; //箭头高度double L = 6; //底边的一半int x3 = 0;int y3 = 0;int x4 = 0;int y4 = 0;double awrad = Math.atan(L / H); //箭头角度double arraow_len = Math.sqrt(L * L + H * H); //箭头的长度double[] arrXY_1 = rotateVec(endX - startX, endY - startY, awrad, true, arraow_len);double[] arrXY_2 = rotateVec(endX - startX, endY - startY, -awrad, true, arraow_len);double x_3 = endX - arrXY_1[0]; //(x3,y3)是第一端点double y_3 = endY - arrXY_1[1];double x_4 = endX - arrXY_2[0]; //(x4,y4)是第二端点double y_4 = endY - arrXY_2[1];Double X3 = new Double(x_3);x3 = X3.intValue();Double Y3 = new Double(y_3);y3 = Y3.intValue();Double X4 = new Double(x_4);x4 = X4.intValue();Double Y4 = new Double(y_4);y4 = Y4.intValue();//画线canvas.drawLine(startX, startY, endX, endY, paint);Path triangle = new Path();triangle.moveTo(endX, endY);triangle.lineTo(x3, y3);triangle.lineTo(x4, y4);triangle.close();canvas.drawPath(triangle, paint);}public double[] rotateVec(float px, float py, double ang, boolean isChLen, double newLen) {double mathstr[] = new double[2];//矢量旋转函数，参数含义分别是x分量、y分量、旋转角、是否改变长度、新长度double vx = px * Math.cos(ang) - py * Math.sin(ang);double vy = px * Math.sin(ang) + py * Math.cos(ang);if (isChLen) {double d = Math.sqrt(vx * vx + vy * vy);vx = vx / d * newLen;vy = vy / d * newLen;mathstr[0] = vx;mathstr[1] = vy;}return mathstr;}/*** 在图片上写字* @param text*/public void writeTextToBitmap(String text) {drawType = 4;this.text = text;invalidate();}public Bitmap writeText() {if (isClear) {isClear = false;finalBitmap = newBitmap;finalTextBitmap = finalBitmap;return finalBitmap;} else {Bitmap bitmap = Bitmap.createScaledBitmap(finalBitmap, mScreenWidth, mScreenHeight, true);Canvas canvas = new Canvas(bitmap);TextPaint textPaint = new TextPaint();textPaint.setColor(textColor);textPaint.setTextSize(textSize * getResources().getDisplayMetrics().density);textPaint.setAntiAlias(true);StaticLayout staticLayout = new StaticLayout(text, textPaint, mScreenWidth * 3 / 4, Layout.Alignment.ALIGN_NORMAL, 1.0f, 0.0f, false);canvas.translate(clickX, clickY);staticLayout.draw(canvas);finalTextBitmap = bitmap;return finalTextBitmap;}}@Overridepublic boolean onTouchEvent(MotionEvent event) {clickX = event.getX();clickY = event.getY();if (event.getAction() == MotionEvent.ACTION_DOWN) {//当按下并不移动时，刷新并记下按下时的坐标点但不绘制startX = clickX;startY = clickY;isMove = false;invalidate();return true;} else if (event.getAction() == MotionEvent.ACTION_MOVE) {//当移动时，进行绘制，从按下的坐标点起if (isEdit) {isMove = true;}invalidate();return true;} else if (event.getAction() == MotionEvent.ACTION_UP) {isMove = false;switch (drawType) {case 1:finalBitmap = finalOvalBitmap;break;case 2:finalBitmap = finalRectBitmap;break;case 3:finalBitmap = finalArrowBitmap;break;}return true;}return super.onTouchEvent(event);}/*** 设置画的类型* @param drawType*/public void setDrawType(int drawType) {if (this.drawType == 4) {finalBitmap = finalTextBitmap;}this.drawType = drawType;}/*** 设置是否允许对图片进行编辑* @param isEdit*/public void setIdEdit(boolean isEdit) {this.isEdit = isEdit;}/*** 清空*/public void clear() {isClear = true;newBitmap = Bitmap.createScaledBitmap(originalBitmap, mScreenWidth, mScreenHeight, true);invalidate();}/*** 设置画笔颜色* @param color*/public void setColor(int color) {this.color = color;}/*** 设置画笔的宽度* @param strokeWidth*/public void setStyle(float strokeWidth) {this.strokeWidth = strokeWidth;}/*** 设置字体大小* @param textSize*/public void setTextSize(int textSize) {this.textSize = textSize;}/*** 设置字体颜色* @param textColor*/public void setTextColor(int textColor) {this.textColor = textColor;}/*** 保存图片*/public void saveBitmap(Handler handler) {if (drawType == 4) {finalBitmap = finalTextBitmap;}if (!filePath.equals(Environment.getExternalStorageDirectory().getPath() + "/JCamera/image.jpeg")) {int bitmapWidth = originalBitmap.getWidth();int bitmapHeight = originalBitmap.getHeight();finalBitmap = Bitmap.createScaledBitmap(finalBitmap, bitmapWidth, bitmapHeight, true);}FileOutputStream fos = null;try {fos = new FileOutputStream(filePath);press(pressFormat.PNG, 90, fos);fos.flush();} catch (IOException e) {e.printStackTrace();} finally {if (fos != null) {try {fos.close();} catch (IOException e) {e.printStackTrace();}}handler.sendMessage(Message.obtain());}}}
以上代码结构很清晰，注释写的也比较清楚。读者可以直接拿去使用。
关于一些基础知识，如果不明白，可以查看我的另一篇文章Canvas、Paint、TextPaint、StaticLayout，或者通过查看Google文档等方式自行了解。
