深圳住房和建设局网站登录,wordpress mp3 缓存,应用中心下载,帝国织梦wordpressCanvas画布#xff0c;通过它我们可以自定义一个View#xff0c;设置View的相关效果之类的。感觉用法差不多#xff0c;重要的是要理解方法中传入的参数的含义#xff0c;比如float类型的参数#xff0c;传递的是坐标,已开是没有注意传入的参数时坐标#xff0c;导致我迷… Canvas画布通过它我们可以自定义一个View设置View的相关效果之类的。感觉用法差不多重要的是要理解方法中传入的参数的含义比如float类型的参数传递的是坐标,已开是没有注意传入的参数时坐标导致我迷糊了一段时间希望大家不要犯我的错误记住是坐标啊。一、Canvas画布介绍The Canvas class holds the “draw” calls. To draw something, you need 4 basic components: A Bitmap to hold the pixels, a Canvas to host the draw calls (writing into the bitmap), a drawing primitive (e.g. Rect, Path, text, Bitmap), and a paint (to describe the colors and styles for the drawing). 关于Canvas网上也没有什么好的介绍 我就直接从API中复制过来的这里翻译一下。 Canvas 支持“绘制”调用想要进行绘制你需要4个基本组成一个由像素构成的位图支持绘制调用的画布绘制位图一个图元如矩形路径文本位图和油漆用于绘制图的颜色和样式。上面的四个基本组成会在后面代码部分进行解释 API中说的究竟是什么意思呢我们可以把这个Canvas理解成系统提供给我们的一块内存区域(但实际上它只是一套画图的API真正的内存是下面的Bitmap)而且它还提供了一整套对这个内存区域进行操作的方法所有的这些操作都是画图API。这样我们就可以在画布上进行绘制了。二、使用步骤 上面说了那么多是不是特别想知道它要怎样使用呢现在我们就来说说他的使用步骤。2.1使用步骤1、写一个class类继承自View2、在继承的class中写它的两个构造器以前的版本中我们只需要写它的两个构造器一个构造器参数为ViewContext另一个构造器参数为 ViewContext AttributeSet 现在版本的升级又新出了两个构造器ViewContext attribute style带有主题样式的不管那么多我们还是只写本来的两个构造器就OK了。3、在该class中调用onDraw方法和onMeasure()方法。4、在布局中使用该View5、进行绘制2.1使用示例 下面我们按照上面的步骤一步步进行1、写一个class类继承自Viewpublic class MyView extends View2、在继承的class中写它的两个构造器public MyView(Context context) { super(context);}public MyView(Context context, AttributeSet attrs) { super(context, attrs);}在该class中重写onDraw方法和onMeasure()方法。onDraw我们将在该方法中进行绘制图形Overrideprotected void onDraw(Canvas canvas) {super.onDraw(canvas);}onMeasure获得画布的高度与宽度Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); width getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec); height getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec); }补充由于onMeasure方法中本身就有获取高度与宽度的方法我们直接点进去ctrl左键复制出来就可以了。在布局中使用该View布局时必须写全包名类名RelativeLayout xmlns:androidhttp://schemas.android.com/apk/res/android xmlns:toolshttp://schemas.android.com/tools android:layout_widthmatch_parent android:layout_heightmatch_parent tools:context.MainActivity com.example.myview.MyView android:layout_widthmatch_parent android:layout_heightmatch_parent5、进行绘制我们要如何进行绘制呢首先我们看些Canvas都能绘制写什么。drawRect(float left, float top, float right, float bottom, Paint paint)//绘制矩形左上右下的坐标,我们可以理解为左上的坐标为我们确定了矩形的左上角点右下坐标为我们确定了右下角的点这样一个矩形区域就确定出来了paint为画笔drawRoundRect(float left, float top, float right, float bottom, float rx, float ry, Paint paint)//绘制圆角矩形左上右下的坐标drawArc(RectF oval, float startAngle, float sweepAngle, boolean useCenter, Paint paint)//绘制弧参数一是RectF对象一个矩形区域椭圆形的界限用于定义在形状、大小、电弧参数二是起始角(度)在电弧的开始参数三扫描角(度)开始顺时针测量的参数四是如果这是真的话,包括椭圆中心的电弧,并关闭它实际绘制的是扇形,如果它是假这将是一个弧线,参数五是Paint对象drawOval(float left, float top, float right, float bottom, Paint paint)//绘制椭圆drawLine(float startX, float startY, float stopX, float stopY, Paint paint)//绘制直线XY起止坐标drawCircle(float cx, float cy, float radius, Paint paint)//绘制圆形drawText(String text, float x, float y, Paint paint)//绘制文本其他的不再进行列举有需要可以查看API文档。在参数中可以看到我们画图是需要画笔的下面我们再来看下画笔画漆。这里展示一段代码相信你就能够明白了。Paint mpaintline new Paint(); mpaintline.setColor(Color.RED); //设置线宽 mpaintline.setStrokeWidth(10); //设置抗锯齿 mpaintline.setAntiAlias(true);//设置空心,比如画实心圆还是空心圆mpaintcircle.setStyle(Paint.Style.STROKE); mpainttext.setTextSize(30); //设置字的位置 mpainttext.setTextAlign(Align.CENTER); mpainttext.setColor(Color.BLACK);2.2表盘示例上面说了那么多我们来看一个具体而完整的实例来整理一下思路。public class MyView extends View private int width; private int height; private Paint mpaintline; private Paint mpaintcircle; private Paint mpainttext; private Calendar mcalendar; private static final int NEED_INVALIDATE0x23; private Handler mhandlernew Handler(){ public void handleMessage(android.os.Message msg) { switch (msg.what) { case NEED_INVALIDATE: //重新获取时间 mcalendarCalendar.getInstance(); //重新绘制界面 invalidate();//告诉UI主线程重新绘制 //再次发送消息递归调用再次监测秒针 mhandler.sendEmptyMessageDelayed(NEED_INVALIDATE, 1000); break; default: break; } }; }; public MyView(Context context) { super(context); } public MyView(Context context, AttributeSet attrs) { //为了不是每次都创建Paint我们在这里创建 super(context, attrs); mcalendarCalendar.getInstance(); mpaintline new Paint(); mpaintline.setColor(Color.RED); //设置线宽 mpaintline.setStrokeWidth(10); //设置抗锯齿 mpaintline.setAntiAlias(true); mpaintcircle new Paint(); mpaintcircle.setColor(Color.GREEN); mpaintcircle.setStrokeWidth(10); //设置空心 mpaintcircle.setStyle(Paint.Style.STROKE); mpainttextnew Paint(); mpainttext.setTextSize(30); mpainttext.setTextAlign(Align.CENTER); mpainttext.setColor(Color.BLACK); //发送消息监测秒针 mhandler.sendEmptyMessage(NEED_INVALIDATE); }//在此方法中进行绘制 Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); //绘制圆形 canvas.drawCircle(width/2, height/2, width/2-20, mpaintcircle); //绘制表芯 canvas.drawCircle(width/2, height/2, 5, mpaintcircle); //绘制表盘时我们采用旋转画布的思想让画布进行旋转一定角度绘制 for(int i1;i12;i){ //保存画布当前状态 canvas.save(); //指定旋转角度与旋转点 canvas.rotate(360/12*i,width/2,height/2); //绘制表盘 canvas.drawLine(width/2, height/2-(width/2-20), width/2,height/2-width/240, mpaintline); //绘制文字 canvas.drawText(i, width/2, height/2-width/270, mpainttext); //恢复开始位置 canvas.restore(); } int minutemcalendar.get(Calendar.MINUTE); int hourmcalendar.get(Calendar.HOUR); int secondmcalendar.get(Calendar.SECOND); float minudegreesminute/60f*360; float hourdregreeshour*60/12f/60*360; float senconddegreesecond/60f*360; //绘制分针 canvas.save(); canvas.rotate(minudegrees,width/2,height/2); canvas.drawLine(width/2, height/2, width/2, height/2-width/290, mpaintline); canvas.restore(); //绘制时针 canvas.save(); canvas.rotate(hourdregrees,width/2,height/2); canvas.drawLine(width/2, height/2, width/2, height/2-width/2100, mpaintline); canvas.restore(); //绘制秒针 canvas.save(); canvas.rotate(senconddegree,width/2,height/2); canvas.drawLine(width/2, height/2, width/2, height/2-width/260, mpaintline); canvas.restore(); } Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); //固定2.3绘制圆形progressbar这里模拟下载自定义了一个ProgressBar。在MyProgressCircle 中定义出最大进度和当前进度给出当前进度的SET\GET方法通过Mainactivity中改变Progres的当前进度根据当前进度不停修改半径重新绘制表层绿色圆形。public class MyProgressCircle extends View{ private int width; private int height; private int Maxprogress100; private int Currentprogress; private Paint PaintBackGround; private Paint PaintCurrent; private Paint PaintText; public int getMaxprogress() { return Maxprogress; } public void setMaxprogress(int maxprogress) { Maxprogress maxprogress; } //当前进度的set、get方法 public int getCurrentprogress() { return Currentprogress; } public void setCurrentprogress(int currentprogress) { Currentprogress currentprogress; invalidate(); } public MyProgressCircle(Context context) { super(context); // TODO Auto-generated constructor stub } public MyProgressCircle(Context context, AttributeSet attrs) { super(context, attrs); PaintBackGroundnew Paint(); PaintBackGround.setColor(Color.GRAY); PaintBackGround.setAntiAlias(true); PaintBackGround.setStrokeWidth(10); PaintCurrentnew Paint(); PaintCurrent.setColor(Color.GREEN); PaintCurrent.setAntiAlias(true); PaintCurrent.setStrokeWidth(10); PaintTextnew Paint(); PaintText.setColor(Color.BLACK); PaintText.setAntiAlias(true); PaintText.setTextAlign(Align.CENTER); } Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); canvas.drawCircle(width/2, height/2,width/2-30 , PaintBackGround); //根据当前进度改变半径绘制圆形 canvas.drawCircle(width/2, height/2,(float) (width/2-30)*Currentprogress/Maxprogress, PaintCurrent); canvas.drawText(Currentprogress*100f/Maxprogress%, width/2,height/2, PaintText); } Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); width getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec); height getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec); }}MainActivity中改变progress进度public class MainActivity extends Activity implements OnClickListener{ private Button btn_circle_progress; private MyProgressCircle myprogresscircle; private int progress; private Handler mhanHandlernew Handler(){ public void handleMessage(android.os.Message msg) { switch (msg.what) { case 0x23: progress; if(progress100){ myprogresscircle.setCurrentprogress(progress); mhanHandler.sendEmptyMessageDelayed(0x23, 200); } break; default: break; } }; }; Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.circle_progress); btn_circle_progress(Button) findViewById(R.id.mbtn_circleprogress); myprogresscircle(MyProgressCircle) findViewById(R.id.mycircleprogress); btn_circle_progress.setOnClickListener(this); } Override public void onClick(View v) { mhanHandler.sendEmptyMessageDelayed(0x23, 1000); }}2.4绘制弧形progressbarOverride protected void onDraw(Canvas canvas) { super.onDraw(canvas); //设置画弧的区域 RectF oval1new RectF(width/2-100,height/2-100,width/2100,height/2100); canvas.drawArc(oval1, 270, Currentprogress, false, PaintCurrent);//第二个参数顺时针起始位置第三个参数顺时针转的弧 canvas.drawText(Currentprogress*100f/Maxprogress%, width/2,height/2, PaintText); }MainActivitypublic class MainActivity_ARC extends Activity implements OnClickListener{ private Button btn_arc_progress; private MyArcProgress myprogressarc; private int progress; private Handler mhanHandlernew Handler(){ public void handleMessage(android.os.Message msg) { switch (msg.what) { case 0x23: progress; if(progress360){ myprogressarc.setCurrentprogress(progress); mhanHandler.sendEmptyMessageDelayed(0x23, 200); } break; default: break; } }; }; Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.arc_progress); btn_arc_progress(Button) findViewById(R.id.mbtn_arcprogress); myprogressarc (MyArcProgress) findViewById(R.id.myarcprogress); btn_arc_progress.setOnClickListener(this); } Override public void onClick(View v) { mhanHandler.sendEmptyMessageDelayed(0x23, 1000); }}2.5绘制多条线与矩形public class MyRectProgress extends View{ private int width; private int height; private int Maxprogress100; private int Currentprogress; private Paint PaintBackGround; private Paint PaintCurrent; private Paint PaintText; private int i; private float[] linesnew float[400]; public int getMaxprogress() { return Maxprogress; } public void setMaxprogress(int maxprogress) { Maxprogress maxprogress; } public int getCurrentprogress() { return Currentprogress; } public void setCurrentprogress(int currentprogress) { Currentprogress currentprogress; lines[i]50; i; lines[i]50250f*Currentprogress/Maxprogress; i; lines[i]300; i; lines[i]50250f*Currentprogress/Maxprogress; invalidate(); } public MyRectProgress(Context context) { super(context); // TODO Auto-generated constructor stub } public MyRectProgress(Context context, AttributeSet attrs) { super(context, attrs); PaintBackGroundnew Paint(); PaintBackGround.setColor(Color.GRAY); PaintBackGround.setAntiAlias(true); PaintBackGround.setStrokeWidth(10); PaintCurrentnew Paint(); PaintCurrent.setColor(Color.GREEN); PaintCurrent.setAntiAlias(true); PaintCurrent.setStrokeWidth(5); PaintTextnew Paint(); PaintText.setColor(Color.BLACK); PaintText.setAntiAlias(true); PaintText.setTextAlign(Align.CENTER); PaintText.setTextSize(30); } Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); //canvas.drawCircle(width/2, height/2,width/2-30 , PaintBackGround); canvas.drawRect(50,50 ,300, 300, PaintBackGround); canvas.drawLines(lines, PaintCurrent); //canvas.drawLine(50,50250f*Currentprogress/Maxprogress, 300, 50250f*Currentprogress/Maxprogress, PaintCurrent); canvas.drawText(Currentprogress*100f/Maxprogress%, width/2,height/2, PaintText); } Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); width getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec); height getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec); }}2.5绘制渐变样式就是我们开始时图片展示的样式package com.example.myview;import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.LinearGradient;import android.graphics.Paint;import android.graphics.Paint.Align;import android.graphics.RectF;import android.graphics.Shader;import android.util.AttributeSet;import android.view.View;public class MyotherProgress extends View{ private int width; private int height; private int Maxprogress100; private int Currentprogress; private Paint PaintBackGround; private Paint PaintCurrent; private Paint PaintText; public int getMaxprogress() { return Maxprogress; } public void setMaxprogress(int maxprogress) { Maxprogress maxprogress; } public int getCurrentprogress() { return Currentprogress; } public void setCurrentprogress(int currentprogress) { Currentprogress currentprogress; invalidate(); } public MyotherProgress(Context context) { super(context); // TODO Auto-generated constructor stub } public MyotherProgress(Context context, AttributeSet attrs) { super(context, attrs); PaintBackGroundnew Paint(); PaintBackGround.setColor(Color.GRAY); PaintBackGround.setAntiAlias(true); PaintBackGround.setStrokeWidth(10); PaintCurrentnew Paint(); PaintCurrent.setColor(Color.GREEN); PaintCurrent.setAntiAlias(true); PaintCurrent.setStrokeWidth(10); /* 设置渐变色 颜色是改变的 */ Shader mShader new LinearGradient(0, 0, 100, 100, new int[] { Color.RED, Color.GREEN, Color.BLUE, Color.YELLOW, Color.LTGRAY }, null, Shader.TileMode.REPEAT); PaintCurrent.setShader(mShader); PaintTextnew Paint(); PaintText.setColor(Color.BLACK); PaintText.setAntiAlias(true); PaintText.setTextAlign(Align.CENTER); PaintText.setTextSize(30); } Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); //底层圆形 canvas.drawCircle(width/2, height/2,width/2-30 , PaintBackGround); // 设置个新的长方形扫描测量 RectF oval new RectF(30,height/2-(width/2-30 ) , width-30 , height/2width/2-30 ); //绘制扇形 // 画弧第一个参数是RectF确定绘制区域 //该类是第二个参数是角度的开始 //第三个参数是多少度 //第四个参数是真的时候画扇形是假的时候画弧线 canvas.drawArc(oval, 0, Currentprogress*360f/100, true, PaintCurrent); canvas.drawText(Currentprogress*100f/Maxprogress%, width/2,height/2, PaintText); } Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); width getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec); height getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec); }}
