Android學習之繪圖入門

Android的繪圖繼承於View組件，重寫onDraw(Canvas canvas) 方法時涉及一個繪圖API: Canvas 代表了依附於指定View的畫布，並且提供了很多繪製方法。

Canvas提供的方法還涉及一個API: Paint ,Paint代表了Canvas上的畫筆，主要用於設定繪製風格，畫筆顏色，粗細，填充風格等。

Path代表任意多條直線串連而成的任意圖形，當Canvas根據Path繪製圖形時，它可以繪製出任意形狀的圖形。

import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.LinearGradient;import android.graphics.Paint;import android.graphics.Path;import android.graphics.RectF;import android.graphics.Shader;import android.util.AttributeSet;import android.view.View;public class MyView extends View {public MyView(Context context, AttributeSet set) {super(context, set);}@Override// 重寫該方法，進行繪圖protected void onDraw(Canvas canvas) {super.onDraw(canvas);// 把整張畫布繪製成白色canvas.drawColor(Color.WHITE);Paint paint = new Paint();// 去鋸齒paint.setAntiAlias(true);paint.setColor(Color.BLUE);paint.setStyle(Paint.Style.STROKE);paint.setStrokeWidth(3);// 繪製圓形canvas.drawCircle(40, 40, 30, paint);// 繪製正方形canvas.drawRect(10, 80, 70, 140, paint);// 繪製矩形canvas.drawRect(10, 150, 70, 190, paint);RectF re1 = new RectF(10, 200, 70, 230);// 繪製圓角矩形canvas.drawRoundRect(re1, 15, 15, paint);RectF re11 = new RectF(10, 240, 70, 270);// 繪製橢圓canvas.drawOval(re11, paint);// 定義一個Path對象，封閉成一個三角形。Path path1 = new Path();path1.moveTo(10, 340);path1.lineTo(70, 340);path1.lineTo(40, 290);path1.close();// 根據Path進行繪製，繪製三角形canvas.drawPath(path1, paint);// 定義一個Path對象，封閉成一個五角形。Path path2 = new Path();path2.moveTo(26, 360);path2.lineTo(54, 360);path2.lineTo(70, 392);path2.lineTo(40, 420);path2.lineTo(10, 392);path2.close();// 根據Path進行繪製，繪製五角形canvas.drawPath(path2, paint);// ----------設定填充風格後繪製----------paint.setStyle(Paint.Style.FILL);paint.setColor(Color.RED);canvas.drawCircle(120, 40, 30, paint);// 繪製正方形canvas.drawRect(90, 80, 150, 140, paint);// 繪製矩形canvas.drawRect(90, 150, 150, 190, paint);RectF re2 = new RectF(90, 200, 150, 230);// 繪製圓角矩形canvas.drawRoundRect(re2, 15, 15, paint);RectF re21 = new RectF(90, 240, 150, 270);// 繪製橢圓canvas.drawOval(re21, paint);Path path3 = new Path();path3.moveTo(90, 340);path3.lineTo(150, 340);path3.lineTo(120, 290);path3.close();// 繪製三角形canvas.drawPath(path3, paint);Path path4 = new Path();path4.moveTo(106, 360);path4.lineTo(134, 360);path4.lineTo(150, 392);path4.lineTo(120, 420);path4.lineTo(90, 392);path4.close();// 繪製五角形canvas.drawPath(path4, paint);// ----------設定漸層器後繪製----------// 為Paint設定漸層器Shader mShader = new LinearGradient(0, 0, 40, 60, new int[] {Color.RED, Color.GREEN, Color.BLUE, Color.YELLOW }, null,Shader.TileMode.REPEAT);paint.setShader(mShader);// 設定陰影paint.setShadowLayer(45, 10, 10, Color.GRAY);// 繪製圓形canvas.drawCircle(200, 40, 30, paint);// 繪製正方形canvas.drawRect(170, 80, 230, 140, paint);// 繪製矩形canvas.drawRect(170, 150, 230, 190, paint);RectF re3 = new RectF(170, 200, 230, 230);// 繪製圓角矩形canvas.drawRoundRect(re3, 15, 15, paint);RectF re31 = new RectF(170, 240, 230, 270);// 繪製橢圓canvas.drawOval(re31, paint);Path path5 = new Path();path5.moveTo(170, 340);path5.lineTo(230, 340);path5.lineTo(200, 290);path5.close();// 根據Path進行繪製，繪製三角形canvas.drawPath(path5, paint);Path path6 = new Path();path6.moveTo(186, 360);path6.lineTo(214, 360);path6.lineTo(230, 392);path6.lineTo(200, 420);path6.lineTo(170, 392);path6.close();// 根據Path進行繪製，繪製五角形canvas.drawPath(path6, paint);// ----------設定字元大小後繪製----------paint.setTextSize(24);paint.setShader(null);// 繪製7個字串canvas.drawText(getResources().getString(R.string.circle), 240, 50,paint);canvas.drawText(getResources().getString(R.string.square), 240, 120,paint);canvas.drawText(getResources().getString(R.string.rect), 240, 175,paint);canvas.drawText(getResources().getString(R.string.round_rect), 230,220, paint);canvas.drawText(getResources().getString(R.string.oval), 240, 260,paint);canvas.drawText(getResources().getString(R.string.triangle), 240, 325,paint);canvas.drawText(getResources().getString(R.string.pentagon), 240, 390,paint);}}