Android 图片处理(Canvas/Paint/Matrix/Path/Bezier曲线)

Android 图片处理(Canvas/Paint/Matrix/Path/Bezier曲线)

本文由 Luzhuo 编写,转发请保留该信息.
原文: https://blog.csdn.net/Rozol/article/details/79683220

加载图片

将图片加载到内存显示之前, 要先根据将要显示的容器的大小来按比例压缩图片, 这样才不至于将内存撑爆.

/*** 加载图片* <br>步骤: 获取手机和图片分辨率 -> 计算缩放比 -> 加载图片(用最大的缩放比)*/
public void onclick(View view){// 获取手机分辨率DispalyHW screenHW = getScreenHeightWidth(this);Log.i(TAG, "手机分辨率: width: " + screenHW.width + " height: " + screenHW.height);// 获取图片分辨率File file = new File(Environment.getExternalStorageDirectory(), "dog.jpg");DispalyHW imageHW = getImageHeightWidth(file);Log.i(TAG, "图片分辨率: width: " + imageHW.width + " height: " + imageHW.height);// 计算缩放比: 图片宽高 ÷ 手机宽高 的比率, 取最大的缩放比int scale = 1;int scalex =  imageHW.width / screenHW.width;int scaley = imageHW.height / screenHW.height;if (scalex >= scaley && scalex > scale) {scale = scalex;}if (scaley > scalex && scaley > scale) {scale = scaley;}Log.i(TAG, "缩放比为: " + scale);// 加载图片Bitmap bitmap = getBitmap(file, scale);imageView.setImageBitmap(bitmap);
}

• 获取手机分辨率

  /*** 获取手机分辨率* @param context*/
  public static DispalyHW getScreenHeightWidth(Context context){DispalyHW hw = new DispalyHW();WindowManager wm = (WindowManager) context.getSystemService(WINDOW_SERVICE);if (Build.VERSION.SDK_INT < Build.VERSION_CODES.HONEYCOMB_MR2) {hw.width = wm.getDefaultDisplay().getWidth();hw.height = wm.getDefaultDisplay().getHeight();} else {// api>13Point point = new Point();wm.getDefaultDisplay().getSize(point);hw.width = point.x;hw.height = point.y;}return hw;
  }

• 获取图片分辨率

  /*** 获取图片的分辨率率* @param file 图片文件* @return 如果文件不存在返回null*/
  public static DispalyHW getImageHeightWidth(File file){if (!file.exists()) return null;DispalyHW hw = new DispalyHW();// bitmap工厂的配置参数BitmapFactory.Options options = new BitmapFactory.Options();options.inJustDecodeBounds = true; // 加载图片信息, 不加载图片BitmapFactory.decodeFile(file.getAbsolutePath(), options);// 获取图片的宽和高hw.width = options.outWidth;hw.height = options.outHeight;return hw;
  }

• 加载图片

  /*** 加载图片* @param file 图片文件* @param scale 缩放比 >= 1* @return 文件不存在返回null*/
  public static Bitmap getBitmap(File file, int scale){if (!file.exists()) return null;BitmapFactory.Options options = new BitmapFactory.Options();options.inSampleSize = scale; // 按缩放比压缩options.inJustDecodeBounds = false; // 加载图片Bitmap bitmap = BitmapFactory.decodeFile(file.getAbsolutePath(), options);return bitmap;
  }

图片处理

只能对副本图片进行处理

创建副本

public void onclick(View view){// 从资源加载BitmapBitmap srcBitmap = getBitmapOnRes(this, R.mipmap.abc);iv_src.setImageBitmap(srcBitmap);// 创作模板Bitmap copyBitmap = Bitmap.createBitmap(srcBitmap.getWidth(), srcBitmap.getHeight(), srcBitmap.getConfig());Canvas canvas = new Canvas(copyBitmap); // 画布Paint paint = new Paint(); // 画笔Matrix matrix = new Matrix(); // 矩阵canvas.drawBitmap(srcBitmap, matrix, paint); // 绘画iv_copy.setImageBitmap(copyBitmap);
}

• 从资源加载图片

  /*** 从资源文件中加载图片* @param context 上下文* @param drawableID 资源图片id*/
  public static Bitmap getBitmapOnRes(Context context, @DrawableRes int drawableID){Bitmap resBitmap = BitmapFactory.decodeResource(context.getResources(), drawableID);return resBitmap;
  }

画布

 /*** 对画布Canvas进行操作, 画布具有 移动, 状态保存与恢复, 绘制等操作*/public void onclick(View view){Bitmap srcBitmap = getBitmapOnRes(this, R.mipmap.abc);iv_src.setImageBitmap(srcBitmap);Bitmap copyBitmap = Bitmap.createBitmap(srcBitmap.getWidth() * 3, srcBitmap.getHeight() * 3, srcBitmap.getConfig());Paint paint = new Paint(); // 画笔paint.setStyle(Paint.Style.STROKE); // 只画线不填充Matrix matrix = new Matrix(); // 矩阵Path path = new Path(); // 路径path.moveTo(10, 50);path.lineTo(30, 100);path.lineTo(60, 300);path.close();Canvas canvas = new Canvas(copyBitmap); // 画布// --- 效果叠加 ---// 平移(参数: x, y)canvas.translate(10, 10);// 缩放(参数: 缩放倍数, x, y)canvas.scale(0.5f, 0.5f, srcBitmap.getWidth() / 2, srcBitmap.getHeight() / 2);// 旋转(参数: 角度, x, y)canvas.rotate(30, srcBitmap.getWidth() / 2, srcBitmap.getHeight() / 2);// --- 画布操作动作的保存与恢复 (仅对 平移等操作有效, 对绘制操作无效) ---// 保存画布修改状态int save = canvas.save();// 还原到最近保存的状态// canvas.restore();// 还原到指定状态canvas.restoreToCount(save);// --- 绘制 ---// 绘制点(参数: x,y / [x,y,x,y,x,y])canvas.drawPoint(10, 10, paint);canvas.drawPoints(new float[]{
   11, 11, 12, 11, 13, 11}, paint);// 绘制文字(参数: 文字, x,y)canvas.drawText("luzhuo.me"