在视图的背景中绘制半圆
在视图的背景中绘制半圆
提问于 2013-04-12 11:51:33
我正在尝试创建一个背景是半圆形的TextView。我使用ShapeDrawable创建一个椭圆。我尝试通过使用ScaleDrawable将椭圆的大小和垂直大小加倍并将其裁剪来创建一个半圆形。但是，ScaleDrawable没有任何效果。为什么不行？在视图的背景中绘制半圆的最佳方法是什么？
res/layout/activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
>
<TextView
android:id="@+id/main_view"
android:background="@drawable/semicircle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true"
android:gravity="center_horizontal"
/>
</RelativeLayout>res/drawable/semicircle.xml
<?xml version="1.0" encoding="utf-8"?>
<scale xmlns:android="http://schemas.android.com/apk/res/android"
android:drawable="@drawable/circle"
android:scaleGravity="top|clip_vertical"
android:scaleHeight="200%"
android:scaleWidth="100%" >
</scale>res/drawable/circle.xml
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="oval"
<solid
android:color="#444" />
</shape>src/.../MainActivity.java
//...
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_activity);
findViewById(R.id.main_view).getBackground().setLevel(10000);
}
//...回答 5
Stack Overflow用户
回答已采纳
发布于 2013-04-12 13:18:06
你可以实现你自己的Drawable。但这不能从XML中夸大。您需要使用View.setBackgroundDrawable()从代码中设置可绘制；
参见我的示例实现，使用drawable绘制一个半圆。
public class SemiCircleDrawable extends Drawable {
private Paint paint;
private RectF rectF;
private int color;
private Direction angle;
public enum Direction
{
LEFT,
RIGHT,
TOP,
BOTTOM
}
public SemiCircleDrawable() {
this(Color.BLUE, Direction.LEFT);
}
public SemiCircleDrawable(int color, Direction angle) {
this.color = color;
this.angle = angle;
paint = new Paint();
paint.setColor(color);
paint.setStyle(Style.FILL);
paint.setAntiAlias(true);
rectF = new RectF();
}
public int getColor() {
return color;
}
/**
* A 32bit color not a color resources.
* @param color
*/
public void setColor(int color) {
this.color = color;
paint.setColor(color);
}
@Override
public void draw(Canvas canvas) {
canvas.save();
Rect bounds = getBounds();
if(angle == Direction.LEFT || angle == Direction.RIGHT)
{
canvas.scale(2, 1);
if(angle == Direction.RIGHT)
{
canvas.translate(-(bounds.right / 2), 0);
}
}
else
{
canvas.scale(1, 2);
if(angle == Direction.BOTTOM)
{
canvas.translate(0, -(bounds.bottom / 2));
}
}
rectF.set(bounds);
if(angle == Direction.LEFT)
canvas.drawArc(rectF, 90, 180, true, paint);
else if(angle == Direction.TOP)
canvas.drawArc(rectF, -180, 180, true, paint);
else if(angle == Direction.RIGHT)
canvas.drawArc(rectF, 270, 180, true, paint);
else if(angle == Direction.BOTTOM)
canvas.drawArc(rectF, 0, 180, true, paint);
canvas.restore()
}
@Override
public void setAlpha(int alpha) {
// Has no effect
}
@Override
public void setColorFilter(ColorFilter cf) {
// Has no effect
}
@Override
public int getOpacity() {
// Not Implemented
return PixelFormat.UNKNOWN;
}
}Stack Overflow用户
发布于 2015-10-26 04:54:50
要裁剪椭圆形，只需将其嵌入到ClipDrawable中，如下所示：
res/drawable/semicircle.xml
<?xml version="1.0" encoding="utf-8"?>
<clip
xmlns:android="http://schemas.android.com/apk/res/android"
android:clipOrientation="vertical"
android:gravity="bottom">
<shape android:shape="oval">
<solid android:color="#444"/>
</shape>
</clip>ClipDdrawable的常见用途是创建自定义进度条。它剪切其内容的一部分，并在其"level“属性在0; 10000范围内增加时逐步显示该内容。
clipOrientation是裁剪进度的方向。gravity是裁剪进度的开始边/边。
要得到一个半圆形，请将此ClipDrawable设置为视图背景，并以编程方式调整其“级别”：
//...
findViewById(R.id.my_view).getBackground().setLevel(5000)
//...适用于所有Android版本(“在API level 1中添加”)，不需要自定义视图。
;-)
Stack Overflow用户
发布于 2014-02-23 03:45:33
我制作了这个类，希望它能帮助你，所有的变量都是西班牙语的，但它很简单，
构造器SemiCirculo使用半圆的rgb和分辨率(半圆的三角形数量)作为参数。
CalcularPuntosPorcentaje方法使用圆的圆心、起始角度、角度的宽度和半径作为参数。
ImprimeCirculo方法以画布为参数，用前一种方法计算出半圆上的点后，再绘制半圆。
CalcularPuntosPorcentaje方法类似于CalcularPuntosPorcentaje，但是在起始和宽度角度参数中，它使用从0到100的%
最后，使用SetOffset和SetColor来更改半圆的角度和颜色的默认起始位置参考
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
public class SemiCirculo {
private Path circulo;
private Paint color;
private float px, py, radio, anguloI, anchoa,offset;
private int r, g, b;
private int resolucion;
private float puntox[],puntoy[];
public SemiCirculo(int r1, int g1, int b1, int resolucion1) {
this.offset = 0;
this.color = new Paint();
this.r = r1;
this.g = g1;
this.b = b1;
this.color.setColor(Color.rgb(r, g, b));
color.setAntiAlias(true);
circulo = new Path();
this.resolucion = resolucion1;
this.puntox = new float[this.resolucion];
this.puntoy = new float[this.resolucion];
this.anguloI = 0;
this.anchoa = 1;
}
public void SetOffset(float off) {
this.offset = off;
}
public void SetColor(int r1,int g1, int b1){
this.r=r1;
this.g=g1;
this.b=b1;
this.color.setColor(Color.rgb(r, g, b));
}
public void CalcularPuntosPorcentaje(float px1, float py1,
float porcentaje, float radio1) {
this.anguloI = 0 + this.offset;
this.px = px1;
this.py = py1;
this.radio = radio1;
this.anguloI = 0;
this.anchoa = porcentaje / 100 * 360;
this.CalcularPuntos(px, py, anguloI, anchoa, radio);
}
public void CalcularPuntos(float px1, float py1, float anguloI1,
float anchoangulo, float radio1) {
this.anguloI = anguloI1 + this.offset;
this.anchoa = anchoangulo;
this.px = px1;
this.py = py1;
this.radio = radio1 ;
float angulo = 360 - this.anguloI - this.anchoa;
for (int i = 0; i < resolucion; i++) {
this.puntox[i] = this.px - (float) Math.sin(Math.toRadians(angulo))
* this.radio;
this.puntoy[i] = this.py - (float) Math.cos(Math.toRadians(angulo))
* this.radio;
angulo = (360 - this.anguloI - this.anchoa)
+ ((this.anchoa / (float) (this.resolucion)) * (i + 2));
}
this.circulo.reset();
this.circulo.moveTo(this.px, this.py);
for (int i = 0; i < resolucion; i++) {
this.circulo.lineTo(this.puntox[i], this.puntoy[i]);
}
}
public void ImprimeCirculo(Canvas canvas) {
canvas.drawPath(this.circulo, this.color);
}
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/15962745
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