android绘图之Canvas基础(2)
Android 绘图学习
1 Canvas 基础
Canvas画布,用于绘制出各种形状配合画布的变幻操作可以绘制出很多复杂图形,基本的绘制图形分类。
提供的绘制函数:
canvas.drawColor();canvas.drawRGB();canvas.drawRect();canvas.drawRoundRect();canvas.drawCircle();canvas.drawPath();canvas.drawLine();canvas.drawArc();canvas.drawOval();canvas.drawPoint();canvas.drawPoints();canvas.drawText();canvas.drawTextOnPath();canvas.drawBitmap();会在后面讲:canvas.drawVertices();canvas.drawPicture();canvas.drawBitmapMesh();canvas.drawTextRun();
2 绘制背景,可以用于初始化和清空画布
//绘制颜色,默认模式public void drawColor(@ColorInt int color) { super.drawColor(color);}//颜色绘制,设置modepublic void drawColor(@ColorInt int color, @NonNull PorterDuff.Mode mode) { super.drawColor(color, mode);}//参数0-255public void drawARGB(int a, int r, int g, int b) { super.drawARGB(a, r, g, b);}//参数0-255public void drawRGB(int r, int g, int b) { super.drawRGB(r, g, b);}
上面四个函数都可以绘制canvas的背景,注意到PorterDuff.Mode变量,它只对两个canvas绘制bitmap起作用,所以此处暂时不讨论mode参数(没有设置mode默认使用srcover porterduff mode)。
canvas.drawColor(Color.BLUE);// canvas.drawColor(Color.GREEN, PorterDuff.Mode.CLEAR);//背景会变成黑色//canvas.drawARGB(150,1,200,57);
3 drawRect 绘制矩形
//传入RectF public void drawRect(@NonNull RectF rect, @NonNull Paint paint) { super.drawRect(rect, paint);}//传入Rectpublic void drawRect(@NonNull Rect r, @NonNull Paint paint) { super.drawRect(r, paint);}//把Rect的四个点坐标传入public void drawRect(float left, float top, float right, float bottom, @NonNull Paint paint) { super.drawRect(left, top, right, bottom, paint);}
Rect 和RectF都是提供一个矩形局域。
(1)精度不一样,Rect是使用int类型作为数值,RectF是使用float类型作为数值。
(2)两个类型提供的方法也不是完全一致。
canvas.drawColor(Color.WHITE);Rect rect1 = new Rect(100, 100, 300, 300);RectF rect2 = new RectF(100, 400, 300, 600);canvas.drawRect(100,700,300,900,mPaint);canvas.drawRect(rect1,mPaint);canvas.drawRect(rect2,mPaint);
4 drawRoundRect :绘制圆角矩形
public void drawRoundRect(@NonNull RectF rect, float rx, float ry, @NonNull Paint paint) { super.drawRoundRect(rect, rx, ry, paint);}//不利用RectF,直接设置四个点public void drawRoundRect(float left, float top, float right, float bottom, float rx, float ry, @NonNull Paint paint) { super.drawRoundRect(left, top, right, bottom, rx, ry, paint);}
**
rect:RectF对象,一个矩形区域。
rx:x方向上的圆角半径。
ry:y方向上的圆角半径。
paint:绘制时所使用的画笔。**
canvas.drawColor(Color.WHITE);RectF rect2 = new RectF(100, 400, 300, 600); canvas.drawRoundRect(rect2,50,50,mPaint);
5 drawCircle绘制圆形
public void drawCircle(float cx, float cy, float radius, @NonNull Paint paint) { super.drawCircle(cx, cy, radius, paint);}
**
cx 圆心x
cy 圆心y
radius半径**
canvas.drawColor(Color.WHITE);canvas.drawCircle(400,400,200,mPaint);
6 drawPath:绘制路径
public void drawPath(@NonNull Path path, @NonNull Paint paint) { super.drawPath(path, paint);}
需要一个Path,代表路径后面会讲解。
Path path = new Path();path.moveTo(200,200);//起点path.lineTo(300,300);path.lineTo(200,600);canvas.drawPath(path,mPaint);
7 drawLine绘制直线
//提供起点,终点和画笔public void drawLine(float startX, float startY, float stopX, float stopY, @NonNull Paint paint) { super.drawLine(startX, startY, stopX, stopY, paint);}public void drawLines(@Size(multiple = 4) @NonNull float[] pts, int offset, int count, @NonNull Paint paint) { super.drawLines(pts, offset, count, paint);}public void drawLines(@Size(multiple = 4) @NonNull float[] pts, @NonNull Paint paint) { super.drawLines(pts, paint);}
绘制线的集合,参数中pts是点的集合,两个值代表一个点,四个值代表一条线,互相之间不连接。
offset跳过的点,count跳过之后要绘制的点的总数,可以用于集合中部分点的绘制。
canvas.drawLine(100,100,500,300,mPaint);float[] positions = {20,20,20,35,40,40,50,87,60,70,90,120};canvas.drawLines(positions,mPaint);float[] positions2 = {20,20,20,35,320,320,320,335,340,340,350,387,360,370,390,420,410,200,90,170};canvas.drawLines(positions2,4,12,mPaint);或者canvas.drawLines(positions2,4,16,mPaint);
跳过部分节点:
没有跳过点
8 drawArc() 绘制圆弧
public void drawArc(@NonNull RectF oval, float startAngle, float sweepAngle, boolean useCenter, @NonNull Paint paint) { super.drawArc(oval, startAngle, sweepAngle, useCenter, paint);}public void drawArc(float left, float top, float right, float bottom, float startAngle, float sweepAngle, boolean useCenter, @NonNull Paint paint) { super.drawArc(left, top, right, bottom, startAngle, sweepAngle, useCenter, paint);}
RectF oval:生成弧的矩形,中心为弧的圆心
float startAngle:弧开始的角度,以X轴正方向为0度,顺时针
float sweepAngle:弧持续的角度
boolean useCenter:是否有弧的两边,True,还两边,False,只有一条弧
RectF rectF1 = new RectF(100, 100, 400, 400);canvas.drawArc(rectF1,0,270,false,mPaint);RectF rectF2 = new RectF(400, 400, 700, 700);canvas.drawArc(rectF2,0,270,true,mPaint);
9 drawOval 绘制椭圆
public void drawOval(@NonNull RectF oval, @NonNull Paint paint) { super.drawOval(oval, paint);}public void drawOval(float left, float top, float right, float bottom, @NonNull Paint paint) { super.drawOval(left, top, right, bottom, paint);}
在矩形框内画一个椭圆,如果是个正方形会画出一个圆。
RectF rectF1 = new RectF(200, 200, 400, 400);RectF rectF2 = new RectF(200, 500, 700, 600);canvas.drawOval(rectF1,mPaint);canvas.drawOval(rectF2,mPaint);
10 drawPoint绘制点:
canvas.drawPoint();
canvas.drawPoints();
public void drawPoint(float x, float y, @NonNull Paint paint) { super.drawPoint(x, y, paint);}public void drawPoints(@Size(multiple = 2) float[] pts, int offset, int count, @NonNull Paint paint) { super.drawPoints(pts, offset, count, paint);}public void drawPoints(@Size(multiple = 2) @NonNull float[] pts, @NonNull Paint paint) { super.drawPoints(pts, paint);}
**
只需要提供两个点一个坐标就可以绘制点。
canvas.drawPoint(20,20,mPaint);
float[] points = {30,40,40,50,60,60};
canvas.drawPoints(points,mPaint);**
11 drawText 绘制文本,drawTextOnPath沿路径绘制文本
public void drawText(@NonNull char[] text, int index, int count, float x, float y, @NonNull Paint paint) { super.drawText(text, index, count, x, y, paint);}public void drawText(@NonNull String text, float x, float y, @NonNull Paint paint) { super.drawText(text, x, y, paint);}public void drawText(@NonNull String text, int start, int end, float x, float y, @NonNull Paint paint) { super.drawText(text, start, end, x, y, paint);}public void drawText(@NonNull CharSequence text, int start, int end, float x, float y, @NonNull Paint paint) { super.drawText(text, start, end, x, y, paint);}
这几种方法类似:
canvas.drawText("好好学习,天天向上",100,100,mPaint);
canvas.drawText("好好学习,天天向上",100,100,mPaint);Path path = new Path();path.addArc(new RectF(100,100,600,600),0,260);canvas.drawTextOnPath("好好学习,天天向上",path,10,10,mPaint);
drawTextOnPath
沿着一条 Path 来绘制文字
text 为所需要绘制的文字
path 为文字的路径
hOffset 文字相对于路径的水平偏移量,用于调整文字的位置
vOffset 文字相对于路径竖直偏移量,用于调整文字的位置
值得注意的是,在绘制 Path 的时候,应该在拐弯处使用圆角,这样文字显示时更舒服
大致讲解,后面会重点讲解。
12 drawBitmap 绘制bitmap
public void drawBitmap(@NonNull Bitmap bitmap, @Nullable Rect src, @NonNull RectF dst, @Nullable Paint paint) { super.drawBitmap(bitmap, src, dst, paint);}public void drawBitmap(@NonNull Bitmap bitmap, @Nullable Rect src, @NonNull Rect dst, @Nullable Paint paint) { super.drawBitmap(bitmap, src, dst, paint);}
Rect src
Rect dst
其中src和dst这两个矩形区域是用来做什么的?
Rect src:指定绘制图片的区域
Rect dst或RectF dst:指定图片在屏幕上的绘制(显示)区域
首先指定图片区域,然后指定绘制图片的区域。
Bitmap bitmap = BitmapFactory.decodeResource(getResources(),R.mipmap.ic_launcher_round);canvas.drawBitmap(bitmap,100,100,mPaint); Rect rect = new Rect(0, 0, 50, 50); Rect rect2 = new Rect(200, 200, 300, 300);canvas.drawBitmap(bitmap,rect,rect2,mPaint);
android绘图之Paint(1)
android绘图之Canvas基础(2)
Android绘图之Path(3)
Android绘图之drawText绘制文本相关(4)
Android绘图之Canvas概念理解(5)
Android绘图之Canvas变换(6)
Android绘图之Canvas状态保存和恢复(7)
Android绘图之PathEffect (8)
Android绘图之LinearGradient线性渐变(9)
Android绘图之SweepGradient(10)
Android绘图之RadialGradient 放射渐变(11)
Android绘制之BitmapShader(12)
Android绘图之ComposeShader,PorterDuff.mode及Xfermode(13)
Android绘图之drawText,getTextBounds,measureText,FontMetrics,基线(14)
Android绘图之贝塞尔曲线简介(15)
Android绘图之PathMeasure(16)
Android 动态修改渐变 GradientDrawable
更多相关文章
- Android(安卓)rom开发:最完整的截屏方案(支持全屏截屏+区域截屏)
- Android(安卓)Activity返回结果startActivityForResult函数
- Android点击EditText之外的地方隐藏键盘
- android surfaceview 指哪画哪升级版!
- android textview文字换行排…
- Android辅助功能AccessibilityService自动全选择文字粘贴模拟输
- android 如何用代码生成圆角Bitmap图片
- Android(安卓)path.op 和canvas.clipPath使用一例
- Android(安卓)自定义字体中英文混合后导致页边距不对的解决方案