Android自定义组件SegmentedGroup源码阅读笔记

类

• LayoutSelector（自定义）： This class is used to provide the proper layout based on the view. Also provides the proper radius for corners. 根据view提供合适的布局, 同时也给四角提供了合适的半径
• Resources： Class for accessing an application’s resources. This sits on top of the asset manager of the application (accessible through getAssets()) and provides a high-level API for getting typed data from the assets. 访问应用资源的类。这个类在AssetManager之上，为从asset中得到数据提供了高等级的API
• ColorStateList: Lets you map View state sets to colors. ColorStateLists are created from XML resource files defined in the “color” subdirectory directory of an application’s resource directory. The XML file contains a single “selector” element with a number of “item” elements inside. 动态的color selector
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获取自定义数据并解析 initAttrs()方法

• TypedArray类似于键值对，可存储id,reference
• 使用Resources.getDimension(int dimenId)得到defValue
• 注意recycle

private void initAttrs(AttributeSet attrs) {        TypedArray typedArray = getContext().getTheme().obtainStyledAttributes(                attrs,                R.styleable.SegmentedGroup,                0, 0);        try {            mMarginDp = (int) typedArray.getDimension(                    R.styleable.SegmentedGroup_border_width,                    getResources().getDimension(R.dimen.radio_button_stroke_border));            mCornerRadius = typedArray.getDimension(                    R.styleable.SegmentedGroup_corner_radius,                    getResources().getDimension(R.dimen.radio_button_conner_radius));            mTintColor = typedArray.getColor(                    R.styleable.SegmentedGroup_tint_color,                    getResources().getColor(R.color.radio_button_selected_color));            mCheckedTextColor = typedArray.getColor(                    R.styleable.SegmentedGroup_checked_text_color,                    getResources().getColor(android.R.color.white));        } finally {            typedArray.recycle();        }    }

动态StateList

• 动态设置按钮的selector, 二维数组[3][?] 对应一维数组[3]

ColorStateList colorStateList = new ColorStateList(new int[][]{                {android.R.attr.state_pressed},                {-android.R.attr.state_pressed, -android.R.attr.state_checked},                {-android.R.attr.state_pressed, android.R.attr.state_checked}},                new int[]{Color.GRAY, mTintColor, mCheckedTextColor});        ((Button) view).setTextColor(colorStateList);

• 动态设置子view的背景

Drawable checkedDrawable = resources.getDrawable(checked).mutate();        Drawable uncheckedDrawable = resources.getDrawable(unchecked).mutate();        ((GradientDrawable) checkedDrawable).setColor(mTintColor);        ((GradientDrawable) checkedDrawable).setStroke(mMarginDp, mTintColor);        ((GradientDrawable) uncheckedDrawable).setStroke(mMarginDp, mTintColor);        //Set proper radius        ((GradientDrawable) checkedDrawable).setCornerRadii(mLayoutSelector.getChildRadii(view));        ((GradientDrawable) uncheckedDrawable).setCornerRadii(mLayoutSelector.getChildRadii(view));        //Create drawable        StateListDrawable stateListDrawable = new StateListDrawable();        stateListDrawable.addState(new int[]{-android.R.attr.state_checked}, uncheckedDrawable);        stateListDrawable.addState(new int[]{android.R.attr.state_checked}, checkedDrawable);        view.setBackground(stateListDrawable);

onFinishInflate()

Finalize inflating a view from XML. This is called as the last phase of inflation, after all child views have been added. 结束xml文件的inflate. 所有的view都已经被添加，最后阶段。

@Override    protected void onFinishInflate() {        super.onFinishInflate();        //Use holo light for default        updateBackground();    }

自定义组件思路

1. 使用TpyedArray从attr获取数据，使用Resources获取默认数据2. 加载父控件，此时不需要自定义操作override3. 当所有子控件都已经填入，使用自定义的方法进行修饰，需要通过封装类考虑横竖屏的情况，此时需要使用到StateList, 自定义selector

问题总结

• context.getResources()， view.getResources()得到的Resources实例没有区别
• Resources中常用方法getColor(int colorId), getDimension(int dimenId), 用来获取colors.xml dimens.xml的id值