先看看圖片的效果，左邊是原圖，右邊是旋轉(zhuǎn)之后的圖；

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之所以把這個(gè)寫出來是因?yàn)樵谝粋€(gè)項(xiàng)目中需要用到這樣的效果，我試過用FrameLayout布局如上的畫面，然后旋轉(zhuǎn)FrameLayout，隨之而來也就存在了一些問題——鋸齒!

在網(wǎng)上搜索之后，有兩種方法，一是利用Paint，二是利用Canvas；
(1)、paint.setAntiAlias(true);

　　 paint.setFlags(Paint.ANTI_ALIAS_FLAG);

(2)、DrawFilter?pfdf = new PaintFlagsDrawFilter(0, Paint.ANTI_ALIAS_FLAG|Paint.FILTER_BITMAP_FLAG);

　　 canvas.setDrawFilter(pfdf);

而如果利用paint,或者canvas，需要從哪獲取paint/canvas，這也是一個(gè)問題；

在實(shí)現(xiàn)的過程中，嘗試過自定義FrameLayout下面的單個(gè)View{ImageView,TextView}，但都以失敗告終，失敗的主要問題在于右圖下邊的文字描述無法和相片邊框相對齊，而且用Matrix旋轉(zhuǎn)背景之后背景大小改變，位置也不在最下邊，所以就采用了單獨(dú)實(shí)現(xiàn)一個(gè)View的方法，主要原因還是因?yàn)樽陨韺anvas繪圖及Paint畫筆不是很熟悉，所以導(dǎo)致的效率不高;

public class RotateTextImageView extends View {PaintFlagsDrawFilter pfdf;Paint paint;Matrix matrix;Bitmap bitmap;int index = -1;private int oriHeight;private int oriWidth;private int newHeight;private int newWidth;private int angle = 5;protected Path path = new Path();private float[] f = new float[8];private int shawHeight = 20;private int borderSize = 8;Bitmap oriBitmap;private String text = "";public RotateTextImageView(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);initCanvasInfo();}public RotateTextImageView(Context context, AttributeSet attrs) {super(context, attrs);initCanvasInfo();}public RotateTextImageView(Context context) {super(context);initCanvasInfo();}/*** 初始化Paint*/protected void initCanvasInfo() {pfdf = new PaintFlagsDrawFilter(0, Paint.ANTI_ALIAS_FLAG| Paint.FILTER_BITMAP_FLAG);paint = new Paint();paint.setAntiAlias(true);matrix = new Matrix();matrix.setRotate(5);}@Overrideprotected void onDraw(Canvas canvas) {super.onDraw(canvas);paint.reset();// 消除鋸齒paint.setAntiAlias(true);paint.setFlags(Paint.ANTI_ALIAS_FLAG);canvas.setDrawFilter(pfdf);canvas.drawBitmap(bitmap, 0, 0, paint);newHeight = bitmap.getHeight();newWidth = bitmap.getWidth();calculatePoints();// 添加陰影 path.reset();path.moveTo(f[0], f[1]);path.lineTo(f[2], f[3]);path.lineTo(f[4], f[5]);path.lineTo(f[6], f[7]);path.close();paint.setStyle(Paint.Style.FILL_AND_STROKE);paint.setColor(Color.parseColor("#96ffffff"));canvas.drawPath(path, paint);// 添加字符if (text != null && !text.equals("")) {path.reset();paint.setTextSize(18);float width = paint.measureText(text);path.moveTo((f[0] + f[2]) / 2, (f[1] + f[3]) / 2);path.lineTo((f[4] + f[6]) / 2, (f[5] + f[7]) / 2);paint.setColor(Color.parseColor("#2b2b2b"));canvas.drawTextOnPath(text, path, (oriWidth - width) / 2, 3, paint);}layout(0, 0, newWidth, newHeight);}/*** 計(jì)算坐標(biāo)值*/private void calculatePoints() {double a = angle * Math.PI / 180;BigDecimal height = new BigDecimal(oriHeight);BigDecimal width = new BigDecimal(oriWidth);BigDecimal cos = new BigDecimal(Math.cos(a));BigDecimal tan = new BigDecimal(Math.tan(a));f[0] = 0;f[1] = height.multiply(cos).floatValue();f[2] = tan.multiply(new BigDecimal(shawHeight)).floatValue();f[3] = (new BigDecimal(f[1])).subtract(new BigDecimal(shawHeight)).floatValue();f[4] = width.multiply(cos).add(new BigDecimal(f[2])).floatValue();f[5] = new BigDecimal(newHeight - shawHeight).floatValue();f[6] = width.multiply(cos).floatValue();f[7] = new BigDecimal(newHeight).floatValue();}/*** 設(shè)置圖片* * @param bmp*/public void setBitmap(Bitmap bmp) {oriBitmap = bmp;matrix.reset();matrix.setRotate(angle);Bitmap bitmapF = addFrame(bmp);oriHeight = bitmapF.getHeight();oriWidth = bitmapF.getWidth();bitmap = Bitmap.createBitmap(bitmapF, 0, 0, bitmapF.getWidth(),bitmapF.getHeight(), matrix, true);postInvalidate();}/*** 旋轉(zhuǎn)角度* * @param angle*/public void setAngle(int angle) {this.angle = angle;setBitmap(oriBitmap);}/*** 設(shè)置底部陰影高度* * @param shawHeight*/public void setShawHeight(int shawHeight) {this.shawHeight = shawHeight;postInvalidate();}/*** 生成添加了白色邊緣的圖* * @param bmp* @return*/protected Bitmap addFrame(Bitmap bmp) {Bitmap bmpWithBorder = Bitmap.createBitmap(bmp.getWidth() + borderSize* 2, bmp.getHeight() + borderSize * 2, bmp.getConfig());Canvas canvas = new Canvas(bmpWithBorder);canvas.drawColor(Color.WHITE);canvas.drawBitmap(bmp, borderSize, borderSize, null);return bmpWithBorder;}/*** 設(shè)置字符串* * @param text*/public void setText(String text) {this.text = text;postInvalidate();}/*** 獲取字體高度*/protected int getFontHeight() {FontMetrics fm = paint.getFontMetrics();return (int) Math.ceil(fm.descent - fm.top) + 2;} }

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　　代碼解釋:其實(shí)沒有什么難的東西，只是一些數(shù)學(xué)運(yùn)算，代碼中每一個(gè)方法都有對應(yīng)的功能注釋。浮點(diǎn)型數(shù)組代表陰影層四個(gè)坐標(biāo)點(diǎn)的八個(gè)坐標(biāo)值，分別是左下、左上、右上、右下四個(gè)點(diǎn)，陰影層坐標(biāo)計(jì)算也比較簡單，但有點(diǎn)繁瑣，就是把原圖旋轉(zhuǎn)之后再根據(jù)幾何知識進(jìn)行求解坐標(biāo)！

　　每次重新設(shè)置角度，設(shè)置圖片，都需要重新繪制圖形-->postInvalidate();

View的使用

一、xml配置文件

<com.livingstone.RotateTextImageViewandroid:id="@+id/myview"android:layout_width="wrap_content"android:layout_height="wrap_content"android:minHeight="250dip"android:minWidth="200dip"android:paddingLeft="5dip" />

二、設(shè)置文字說明及角度、圖片

RotateTextImageView myView = (RotateTextImageView) findViewById(R.id.myview);myView.setShawHeight(50);Bitmap bmp = BitmapFactory.decodeResource(getResources(),R.drawable.test1);myView.setBitmap(bmp);myView.setAngle(10);myView.setText("這是一個(gè)測試");

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Ex:獲取字體寬度的兩種方法
<1>.通過paint獲取字體的Rect

Rect rect=newRect(); paint.getTextBounds("你好",0,1, rect); Log.v("a:","height:"+rect.height()+"width:"+rect.width());

<2>.通過paint直接獲取字體寬度

intwidth=(int)paint.measureText("你好",0,1); Log.v("width:","width:"+width);

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轉(zhuǎn)載于:https://www.cnblogs.com/a284628487/p/3377925.html

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