本範例將運用Paint對象(繪筆)的設置值不同,在Cavas(畫布)上繪製空心、實習及漸變色的多種幾何多形。
範例說明
“如何在和機上繪製2D圖形呢?”這是許多android遊戲開發都是常提到的問題,在android SDK 當中,並沒有Java Graphics2D的函數可以使用,而是使用android.graphics底下的類來繪製2D向量圖。這個package提供了許多在手機上繪製圖 形的類與方法,其中Canvas上,而Paint(Android.graphics.Paint)類則像是彩色鉛筆,給予不同的調協,即可繪製不同顏 色、不同種類效果的向量圖形。
本範例將運用Paint對象(繪筆)的設置值不同,在Cavas(畫布)上繪製空心、實習及漸變色的多種幾何多形。
運行結果如果
範例程序
主程序中繼承自Android.view.View的 MyView類,重寫 MyView的onDraw()方法,一開始就會運行繪製的工作,在onDraw()中以Paint將幾何圖形繪製在Canvas上,以 paint.setColor() 改變圖形顏色、以 paint.setStyle()的設置來控制畫出的的圖形是空心還是實心。程序的最後一段,就是直接在Canvas寫上文字,隨着Paint對象裏的屬 性設置,也會有不同的外觀模式。
de<package com.graphices;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.RectF;
import android.graphics.Path;
import android.graphics.Shader;
import android.graphics.LinearGradient;
public class GraphicesActivity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
/*設置ContentView爲自定義的MyVieW*/
MyView myView=new MyView(this);
setContentView(myView);
}
/* 自定義繼承View 的MyView*/
private class MyView extends View
{
public MyView(Context context){
super(context) ;
}
/*重寫onDraw()*/
@Override
protected void onDraw(Canvas canvas)
{
super.onDraw(canvas);
/*設置背景爲白色*/
canvas.drawColor(Color.WHITE);
Paint paint=new Paint();
/*去鋸齒*/
paint.setAntiAlias(true);
/*設置paint的顏色*/
paint.setColor(Color.RED);
/*設置paint的 style 爲STROKE:空心*/
paint.setStyle(Paint.Style.STROKE);
/*設置paint的外框寬度*/
paint.setStrokeWidth(3);
/*畫一個空心圓形*/
canvas.drawCircle(40, 40, 30, paint);
/*畫一個空心正方形*/
canvas.drawRect(10, 90, 70, 150, paint);
/*畫一個空心長方形*/
canvas.drawRect(10, 170, 70,200, paint);
/*畫一個空心橢圓形*/
RectF re=new RectF(10,220,70,250);
canvas.drawOval(re, paint);
/*畫一個空心三角形*/
Path path=new Path();
path.moveTo(10, 330);
path.lineTo(70,330);
path.lineTo(40,270);
path.close();
canvas.drawPath(path, paint);
/* 畫一個空心梯形*/
Path path1=new Path();
path1.moveTo(10, 410);
path1.lineTo(70,410);
path1.lineTo(55,350);
path1.lineTo(25, 350);
path1.close();
canvas.drawPath(path1, paint);
/*設置paint 的style爲 FILL:實心*/
paint.setStyle(Paint.Style.FILL);
/*設置paint的顏色*/
paint.setColor(Color.BLUE);
/*畫一個實心圓*/
canvas.drawCircle(120,40,30, paint);
/*畫一個實心正方形*/
canvas.drawRect(90, 90, 150, 150, paint);
/*畫一個實心長方形*/
canvas.drawRect(90, 170, 150,200, paint);
/*畫一個實心橢圓*/
RectF re2=new RectF(90,220,150,250);
canvas.drawOval(re2, paint);
/*畫一個實心三角形*/
Path path2=new Path();
path2.moveTo(90, 330);
path2.lineTo(150,330);
path2.lineTo(120,270);
path2.close();
canvas.drawPath(path2, paint);
/*畫一個實心梯形*/
Path path3=new Path();
path3.moveTo(90, 410);
path3.lineTo(150,410);
path3.lineTo(135,350);
path3.lineTo(105, 350);
path3.close();
canvas.drawPath(path3, paint);
/*設置漸變色*/
Shader mShader=new LinearGradient(0,0,100,100,
new int[]{Color.RED,Color.GREEN,Color.BLUE,Color.YELLOW},
null,Shader.TileMode.REPEAT);
paint.setShader(mShader);
/*畫一個漸變色圓*/
canvas.drawCircle(200,40,30, paint);
/*畫一個漸變色正方形*/
canvas.drawRect(170, 90, 230, 150, paint);
/*畫一個漸變色長方形*/
canvas.drawRect(170, 170, 230,200, paint);
/*畫一個漸變色橢圓*/
RectF re3=new RectF(170,220,230,250);
canvas.drawOval(re3, paint);
/*畫一個漸變色三角形*/
Path path4=new Path();
path4.moveTo(170,330);
path4.lineTo(230,330);
path4.lineTo(200,270);
path4.close();
canvas.drawPath(path4, paint);
/*畫一個漸變色梯形*/
Path path5=new Path();
path5.moveTo(170, 410);
path5.lineTo(230,410);
path5.lineTo(215,350);
path5.lineTo(185, 350);
path5.close();
canvas.drawPath(path5, paint);
/*寫字*/
paint.setTextSize(24);
canvas.drawText(getResources().getString(R.string.str_text1), 240, 50, paint);
canvas.drawText(getResources().getString(R.string.str_text2), 240, 120, paint);
canvas.drawText(getResources().getString(R.string.str_text3), 240, 190, paint);
canvas.drawText(getResources().getString(R.string.str_text4), 240, 250, paint);
canvas.drawText(getResources().getString(R.string.str_text5), 240, 320, paint);
canvas.drawText(getResources().getString(R.string.str_text6), 240, 390, paint);
}
}
}de<