android进阶-Android控件架构与自定义控件详解（一）

[demo下载地址]

1.Android控件架构

2.View的测量

public class TeachingView extends View {

public TeachingView(Context context) {
super(context);
}

public TeachingView(Context context, AttributeSet attrs) {
super(context, attrs);
}

public TeachingView(Context context, AttributeSet attrs,
int defStyleAttr) {
super(context, attrs, defStyleAttr);
}

/**
* 重写onMeasure方法
* @param widthMeasureSpec
* @param heightMeasureSpec
*/
@Override
protected void onMeasure(int widthMeasureSpec,
int heightMeasureSpec) {
setMeasuredDimension(
measureWidth(widthMeasureSpec),
measureHeight(heightMeasureSpec));
}

private int measureWidth(int measureSpec) {
int result = 0;
//第一步：从measureSpec对象中提取出具体的测量模式和大小
int specMode = MeasureSpec.getMode(measureSpec);
int specSize = MeasureSpec.getSize(measureSpec);

//第二步：通过判断测量的模式，给出不同的测量值。
//当specMode为EXACTLY时，直接指定的specSize即可，
//当specMode为其他模式时，需要给它一个默认的大小
if (specMode == MeasureSpec.EXACTLY) {
result = specSize;
} else {
result = 200;
if (specMode == MeasureSpec.AT_MOST) {
result = Math.min(result, specSize);
}
}
return result;
}

private int measureHeight(int measureSpec) {
int result = 0;
int specMode = MeasureSpec.getMode(measureSpec);
int specSize = MeasureSpec.getSize(measureSpec);

if (specMode == MeasureSpec.EXACTLY) {
result = specSize;
} else {
result = 200;
if (specMode == MeasureSpec.AT_MOST) {
result = Math.min(result, specSize);
}
}
return result;
}

@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawColor(Color.GRAY);
int width = getWidth();
int height = getHeight();
Log.d("xys", "width : " + width + " height : " + height);
}
}

3.View的绘制

4.ViewGroup的测量

5.ViewGroup的绘制

6.自定义View

public class ShineTextView extends TextView {

private LinearGradient mLinearGradient;
private Matrix mGradientMatrix;
private Paint mPaint;
private int mViewWidth = 0;
private int mTranslate = 0;

public ShineTextView(Context context, AttributeSet attrs) {
super(context, attrs);
}

/**
* 进行一些对象的初始化工作，并根据View的宽设置一个LinearGradient渐变渲染器
* @param w
* @param h
* @param oldw
* @param oldh
*/
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
if (mViewWidth == 0) {
mViewWidth = getMeasuredWidth();
if (mViewWidth > 0) {
mPaint = getPaint();
mLinearGradient = new LinearGradient(
0,
0,
mViewWidth,
0,
new int[]{
Color.BLUE, 0xffffffff,
Color.BLUE},
null,
Shader.TileMode.CLAMP);
mPaint.setShader(mLinearGradient);
mGradientMatrix = new Matrix();
}
}
}

/**
* 最关键给Paint对象设置原生TextView没有的LinearGradient属性
* 通过矩阵的方式来不断平移渐变效果
* @param canvas
*/
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
if (mGradientMatrix != null) {
mTranslate += mViewWidth / 5;
if (mTranslate > 2 * mViewWidth) {
mTranslate = -mViewWidth;
}
mGradientMatrix.setTranslate(mTranslate, 0);
mLinearGradient.setLocalMatrix(mGradientMatrix);
postInvalidateDelayed(100);
}
}
}

<?xml version="1.0" encoding="utf-8"?>
<resources>

<declare-styleable name="TopBar">
<attr name="title" format="string" />
<attr name="titleTextSize" format="dimension" />
<attr name="titleTextColor" format="color" />
<attr name="leftTextColor" format="color" />
<attr name="leftBackground" format="reference|color" />
<attr name="leftText" format="string" />
<attr name="rightTextColor" format="color" />
<attr name="rightBackground" format="reference|color" />
<attr name="rightText" format="string" />
</declare-styleable>

</resources>

// 为组件元素设置相应的布局元素
mLeftParams = new LayoutParams(
LayoutParams.WRAP_CONTENT,
LayoutParams.MATCH_PARENT);
mLeftParams.addRule(RelativeLayout.ALIGN_PARENT_LEFT, TRUE);
// 添加到ViewGroup
addView(mLeftButton, mLeftParams);

mRightParams = new LayoutParams(
LayoutParams.WRAP_CONTENT,
LayoutParams.MATCH_PARENT);
mRightParams.addRule(RelativeLayout.ALIGN_PARENT_RIGHT, TRUE);
addView(mRightButton, mRightParams);

mTitlepParams = new LayoutParams(
LayoutParams.WRAP_CONTENT,
LayoutParams.MATCH_PARENT);
mTitlepParams.addRule(RelativeLayout.CENTER_IN_PARENT, TRUE);
addView(mTitleView, mTitlepParams);

public class TopBar extends RelativeLayout {

// 包含topbar上的元素：左按钮、右按钮、标题
private Button mLeftButton, mRightButton;
private TextView mTitleView;

// 布局属性，用来控制组件元素在ViewGroup中的位置
private LayoutParams mLeftParams, mTitlepParams, mRightParams;

// 左按钮的属性值，即我们在atts.xml文件中定义的属性
private int mLeftTextColor;
private Drawable mLeftBackground;
private String mLeftText;
// 右按钮的属性值，即我们在atts.xml文件中定义的属性
private int mRightTextColor;
private Drawable mRightBackground;
private String mRightText;
// 标题的属性值，即我们在atts.xml文件中定义的属性
private float mTitleTextSize;
private int mTitleTextColor;
private String mTitle;

// 映射传入的接口对象
private topbarClickListener mListener;

public TopBar(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}

public TopBar(Context context) {
super(context);
}

public TopBar(Context context, AttributeSet attrs) {
super(context, attrs);
// 设置topbar的背景
setBackgroundColor(0xFFF59563);
// 通过这个方法，将你在atts.xml中定义的declare-styleable
// 的所有属性的值存储到TypedArray中
TypedArray ta = context.obtainStyledAttributes(attrs,
R.styleable.TopBar);
// 从TypedArray中取出对应的值来为要设置的属性赋值
mLeftTextColor = ta.getColor(
R.styleable.TopBar_leftTextColor, 0);
mLeftBackground = ta.getDrawable(
R.styleable.TopBar_leftBackground);
mLeftText = ta.getString(R.styleable.TopBar_leftText);

mRightTextColor = ta.getColor(
R.styleable.TopBar_rightTextColor, 0);
mRightBackground = ta.getDrawable(
R.styleable.TopBar_rightBackground);
mRightText = ta.getString(R.styleable.TopBar_rightText);

mTitleTextSize = ta.getDimension(
R.styleable.TopBar_titleTextSize, 10);
mTitleTextColor = ta.getColor(
R.styleable.TopBar_titleTextColor, 0);
mTitle = ta.getString(R.styleable.TopBar_title);

// 获取完TypedArray的值后，一般要调用
// recyle方法来避免重新创建的时候的错误
ta.recycle();

mLeftButton = new Button(context);
mRightButton = new Button(context);
mTitleView = new TextView(context);

// 为创建的组件元素赋值
// 值就来源于我们在引用的xml文件中给对应属性的赋值
mLeftButton.setTextColor(mLeftTextColor);
mLeftButton.setBackground(mLeftBackground);
mLeftButton.setText(mLeftText);

mRightButton.setTextColor(mRightTextColor);
mRightButton.setBackground(mRightBackground);
mRightButton.setText(mRightText);

mTitleView.setText(mTitle);
mTitleView.setTextColor(mTitleTextColor);
mTitleView.setTextSize(mTitleTextSize);
mTitleView.setGravity(Gravity.CENTER);

// 为组件元素设置相应的布局元素
mLeftParams = new LayoutParams(
LayoutParams.WRAP_CONTENT,
LayoutParams.MATCH_PARENT);
mLeftParams.addRule(RelativeLayout.ALIGN_PARENT_LEFT, TRUE);
// 添加到ViewGroup
addView(mLeftButton, mLeftParams);

mRightParams = new LayoutParams(
LayoutParams.WRAP_CONTENT,
LayoutParams.MATCH_PARENT);
mRightParams.addRule(RelativeLayout.ALIGN_PARENT_RIGHT, TRUE);
addView(mRightButton, mRightParams);

mTitlepParams = new LayoutParams(
LayoutParams.WRAP_CONTENT,
LayoutParams.MATCH_PARENT);
mTitlepParams.addRule(RelativeLayout.CENTER_IN_PARENT, TRUE);
addView(mTitleView, mTitlepParams);

// 按钮的点击事件，不需要具体的实现，
// 只需调用接口的方法，回调的时候，会有具体的实现
mRightButton.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {
mListener.rightClick();
}
});

mLeftButton.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {
mListener.leftClick();
}
});
}

// 暴露一个方法给调用者来注册接口回调
// 通过接口来获得回调者对接口方法的实现
public void setOnTopbarClickListener(topbarClickListener mListener) {
this.mListener = mListener;
}

/**
* 设置按钮的显示与否 通过id区分按钮，flag区分是否显示
*
* @param id   id
* @param flag 是否显示
*/
public void setButtonVisable(int id, boolean flag) {
if (flag) {
if (id == 0) {
mLeftButton.setVisibility(View.VISIBLE);
} else {
mRightButton.setVisibility(View.VISIBLE);
}
} else {
if (id == 0) {
mLeftButton.setVisibility(View.GONE);
} else {
mRightButton.setVisibility(View.GONE);
}
}
}

// 接口对象，实现回调机制，在回调方法中
// 通过映射的接口对象调用接口中的方法
// 而不用去考虑如何实现，具体的实现由调用者去创建
public interface topbarClickListener {
// 左按钮点击事件
void leftClick();
// 右按钮点击事件
void rightClick();
}
}

public class TopBarTest extends Activity {

private TopBar mTopbar;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.topbar_test);
// 获得我们创建的topbar
mTopbar = (TopBar) findViewById(R.id.topBar);
// 为topbar注册监听事件，传入定义的接口
// 并以匿名类的方式实现接口内的方法
mTopbar.setOnTopbarClickListener(
new TopBar.topbarClickListener() {

@Override
public void rightClick() {
Log.e("xyz","1111111111");
Toast.makeText(TopBarTest.this,
"right", Toast.LENGTH_SHORT)
.show();
}

@Override
public void leftClick() {
Log.e("xyz","2222222222");
Toast.makeText(TopBarTest.this,
"left", Toast.LENGTH_SHORT)
.show();
}
});
// 控制topbar上组件的状态
mTopbar.setButtonVisable(0, true);
mTopbar.setButtonVisable(1, true);
}
}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:custom="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="5dp"
tools:context=".MainActivity">

<!-- <include layout="@layout/topbar" /> -->

<com.imooc.systemwidget.TopBar
android:id="@+id/topBar"
android:layout_width="match_parent"
android:layout_height="40dp"
custom:leftBackground="@drawable/blue_button"
custom:leftText="Back"
custom:leftTextColor="#FFFFFF"
custom:rightBackground="@drawable/blue_button"
custom:rightText="More"
custom:rightTextColor="#FFFFFF"
custom:title="自定义标题"
custom:titleTextColor="#123412"
custom:titleTextSize="10sp"/>

</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?>
<resources>

<declare-styleable name="TopBar">
<attr name="title" format="string" />
<attr name="titleTextSize" format="dimension" />
<attr name="titleTextColor" format="color" />
<attr name="leftTextColor" format="color" />
<attr name="leftBackground" format="reference|color" />
<attr name="leftText" format="string" />
<attr name="rightTextColor" format="color" />
<attr name="rightBackground" format="reference|color" />
<attr name="rightText" format="string" />
</declare-styleable>

</resources>