Android自定义控件：自定义属性
当Android提供的原生属性不能满足实际的需求的时候，比如我们需要自定义饼图的百分比半径大小、圆形背景、圆形显示的位置、圆形进度的背景等等。这个时候就需要我们自定义属性了。
自定义属性步骤：
1.attrs.xml文件
在res/values文件下添加一个attrs.xml文件，如果项目比较大的话，会导致attrs.xml代码相当庞大，这时可以根据相应的功能模块起名字，方便查找，例如：登录模块相关attrs_login.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="RoundImageView">
<attr name="borderRadius" />
<attr name="type" />
</declare-styleable>
</resources>
2.声明一组属性
使用<declare-styleable name="PercentView"></declare-styleable>来定义一个属性集合，name就是属性集合的名字，这个名字一定要起的见名知意。
<declare-styleable name="PercentView">
<!--添加属性-->
</declare-styleable>
然后就是定义属性值了，通过<attr name="textColor" format="color" /> 方式定义属性值，属性名字同样也要起的见名知意，format表示这个属性的值的类型,类型有以下几种:
reference:引用资源
string:字符串
Color：颜色
boolean：布尔值
dimension：尺寸值
float：浮点型
integer：整型
fraction：百分数
enum：枚举类型
flag：位或运算
基于上面的要求，我们可以定义一下百分比控件属性
<declare-styleable name="PercentView">
<attr name="percent_circle_gravity"><!--圆形绘制的位置-->
<flag name="left" value="0" />
<flag name="top" value="1" />
<flag name="center" value="2" />
<flag name="right" value="3" />
<flag name="bottom" value="4" />
</attr>
<attr name="percent_circle_radius" format="dimension" /><!--圆形半径-->
<attr name="percent_circle_progress" format="integer" /><!--当前进度值-->
<attr name="percent_progress_color" format="color" /><!--进度显示颜色-->
<attr name="percent_background_color" format="color" /><!--圆形背景色-->
</declare-styleable>
3.布局中如何使用
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:lee="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<com.whoislcj.views.PercentView
android:layout_width="200dp"
android:layout_height="200dp"
android:layout_margin="10dp"
android:background="@color/red"
android:padding="10dp"
lee:percent_background_color="@color/gray"
lee:percent_circle_gravity="left"
lee:percent_circle_progress="30"
lee:percent_circle_radius="50dp"
lee:percent_progress_color="@color/blue" />
</LinearLayout>
为属性集设置一个属性集名称，我这里用的lee，我这是因为实在想不起使用什么属性集名称了，建议在真正的项目中使用项目的缩写，比如微信可能就是使用wx。
4.自定义控件中如何获取自定义属性
每一个属性集合编译之后都会对应一个styleable对象，通过styleable对象获取TypedArray typedArray，然后通过键值对获取属性值，这点有点类似SharedPreference的取法。
TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.PercentView);
if (typedArray != null) {
backgroundColor = typedArray.getColor(R.styleable.PercentView_percent_background_color, Color.GRAY);
progressColor = typedArray.getColor(R.styleable.PercentView_percent_progress_color, Color.BLUE);
radius = typedArray.getDimension(R.styleable.PercentView_percent_circle_radius, 0);
progress = typedArray.getInt(R.styleable.PercentView_percent_circle_progress, 0);
gravity = typedArray.getInt(R.styleable.PercentView_percent_circle_gravity, CENTER);
typedArray.recycle();
}
5.完整示例
public class PercentView extends View {
private final static String TAG = PercentView.class.getSimpleName();
private Paint mPaint;
private int backgroundColor = Color.GRAY;
private int progressColor = Color.BLUE;
private float radius;
private int progress;
private float centerX = 0;
private float centerY = 0;
public static final int LEFT = 0;
public static final int TOP = 1;
public static final int CENTER = 2;
public static final int RIGHT = 3;
public static final int BOTTOM = 4;
private int gravity = CENTER;
private RectF rectF; //用于定义的圆弧的形状和大小的界限
public PercentView(Context context) {
super(context);
init();
}
public PercentView(Context context, AttributeSet attrs) {
super(context, attrs);
initParams(context, attrs);
}
public PercentView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
initParams(context, attrs);
}
private void init() {
mPaint = new Paint();
mPaint.setAntiAlias(true);
rectF = new RectF();
}
private void initParams(Context context, AttributeSet attrs) {
mPaint = new Paint();
mPaint.setAntiAlias(true);
rectF = new RectF();
TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.PercentView);
if (typedArray != null) {
backgroundColor = typedArray.getColor(R.styleable.PercentView_percent_background_color, Color.GRAY);
progressColor = typedArray.getColor(R.styleable.PercentView_percent_progress_color, Color.BLUE);
radius = typedArray.getDimension(R.styleable.PercentView_percent_circle_radius, 0);
progress = typedArray.getInt(R.styleable.PercentView_percent_circle_progress, 0);
gravity = typedArray.getInt(R.styleable.PercentView_percent_circle_gravity, CENTER);
typedArray.recycle();
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int widthMode = MeasureSpec.getMode(widthMeasureSpec);
int widthSize = MeasureSpec.getSize(widthMeasureSpec);
int heightMode = MeasureSpec.getMode(heightMeasureSpec);
int heightSize = MeasureSpec.getSize(heightMeasureSpec);
Log.e(TAG, "onMeasure--widthMode-->" + widthMode);
switch (widthMode) {
case MeasureSpec.EXACTLY://
break;
case MeasureSpec.AT_MOST:
break;
case MeasureSpec.UNSPECIFIED:
break;
}
Log.e(TAG, "onMeasure--widthSize-->" + widthSize);
Log.e(TAG, "onMeasure--heightMode-->" + heightMode);
Log.e(TAG, "onMeasure--heightSize-->" + heightSize);
int with = getWidth();
int height = getHeight();
Log.e(TAG, "onDraw---->" + with + "*" + height);
centerX = widthSize / 2;
centerY = heightSize / 2;
switch (gravity) {
case LEFT:
centerX = radius + getPaddingLeft();
break;
case TOP:
centerY = radius + getPaddingTop();
break;
case CENTER:
break;
case RIGHT:
centerX = with - radius - getPaddingRight();
break;
case BOTTOM:
centerY = height - radius - getPaddingBottom();
break;
}
float left = centerX - radius;
float top = centerY - radius;
float right = centerX + radius;
float bottom = centerY + radius;
rectF.set(left, top, right, bottom);
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
Log.e(TAG, "onLayout");
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
mPaint.setColor(backgroundColor);
// FILL填充, STROKE描边,FILL_AND_STROKE填充和描边
mPaint.setStyle(Paint.Style.FILL_AND_STROKE);
canvas.drawCircle(centerX, centerY, radius, mPaint);
mPaint.setColor(progressColor);
double percent = progress * 1.0 / 100;
int angle = (int) (percent * 360);
canvas.drawArc(rectF, 270, angle, true, mPaint); //根据进度画圆弧
}
}