对Qmui 实现半透明的分析

public class QMUIAlphaViewHelper {
    private WeakReference mTarget;

    
    private boolean mChangeAlphaWhenPress = true;

    
    private boolean mChangeAlphaWhenDisable = true;

    private float mNormalAlpha = 1f;
    private float mPressedAlpha = .5f;
    private float mDisabledAlpha = .5f;

    public QMUIAlphaViewHelper(@NonNull View target) {
        mTarget = new WeakReference<>(target);
        mPressedAlpha = getAttrFloatValue(target.getContext(), R.attr.qmui_alpha_pressed);
        mDisabledAlpha = getAttrFloatValue(target.getContext(), R.attr.qmui_alpha_disabled);
    }

    public QMUIAlphaViewHelper(@NonNull View target, float pressedAlpha, float disabledAlpha) {
        mTarget = new WeakReference<>(target);
        mPressedAlpha = pressedAlpha;
        mDisabledAlpha = disabledAlpha;
    }


    public void setPressedAlpha(float mPressedAlpha) {
        this.mPressedAlpha = mPressedAlpha;
    }

    public void setDisabledAlpha(float mDisabledAlpha) {
        this.mDisabledAlpha = mDisabledAlpha;
    }

    
    public void onPressedChanged(View current, boolean pressed) {
        View targetView = mTarget.get();
        if (targetView == null) {
            return;
        }
        if (current.isEnabled()) {
            if (mChangeAlphaWhenPress && pressed && current.isClickable()) {
                targetView.setAlpha(mPressedAlpha);
            } else {
                targetView.setAlpha(mNormalAlpha);
            }
        }
    }


    
    public void setChangeAlphaWhenPress(boolean changeAlphaWhenPress) {
        mChangeAlphaWhenPress = changeAlphaWhenPress;
    }

    
    public void setChangeAlphaWhenDisable(boolean changeAlphaWhenDisable) {
        mChangeAlphaWhenDisable = changeAlphaWhenDisable;
        View target = mTarget.get();
        if (target != null) {
            onEnabledChanged(target, target.isEnabled());
        }

    }


    
    public void onEnabledChanged(View current, boolean enabled) {
        View target = mTarget.get();
        if (target == null) {
            return;
        }
        float alphaForIsEnable;
        if (mChangeAlphaWhenDisable) {
            alphaForIsEnable = enabled ? mNormalAlpha : mDisabledAlpha;
        } else {
            alphaForIsEnable = mNormalAlpha;
        }
        if (current != target && target.isEnabled() != enabled) {
            target.setEnabled(enabled);
        }
        target.setAlpha(alphaForIsEnable);
    }


    private static TypedValue sTmpValue;

    public static float getAttrFloatValue(Context context, int attr) {
        return getAttrFloatValue(context.getTheme(), attr);
    }

    public static float getAttrFloatValue(Resources.Theme theme, int attr) {
        if (sTmpValue == null) {
            sTmpValue = new TypedValue();
        }
        if (!theme.resolveAttribute(attr, sTmpValue, true)) {
            return 0;
        }
        return sTmpValue.getFloat();
    }
}

public interface QMUIAlphaViewInf {



    
    void setChangeAlphaWhenPress(boolean changeAlphaWhenPress);

    
    void setChangeAlphaWhenDisable(boolean changeAlphaWhenDisable);


}

import android.content.Context;
import android.util.AttributeSet;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.widget.AppCompatButton;

public class QmuiAlphaButton extends AppCompatButton implements QMUIAlphaViewInf {
    private QMUIAlphaViewHelper mAlphaViewHelper;

    public QmuiAlphaButton(@NonNull Context context) {
        super(context);
    }

    public QmuiAlphaButton(@NonNull Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

    public QmuiAlphaButton(@NonNull Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    private QMUIAlphaViewHelper getAlphaViewHelper() {
        if (mAlphaViewHelper == null) {
            mAlphaViewHelper = new QMUIAlphaViewHelper(this);
        }
        return mAlphaViewHelper;
    }

    @Override
    public void setPressed(boolean pressed) {
        super.setPressed(pressed);
        getAlphaViewHelper().onPressedChanged(this, pressed);
    }

    @Override
    public void setEnabled(boolean enabled) {
        super.setEnabled(enabled);
        getAlphaViewHelper().onEnabledChanged(this, enabled);
    }

    @Override
    public void setChangeAlphaWhenPress(boolean changeAlphaWhenPress) {
        getAlphaViewHelper().setChangeAlphaWhenPress(changeAlphaWhenPress);
    }

    @Override
    public void setChangeAlphaWhenDisable(boolean changeAlphaWhenDisable) {
        getAlphaViewHelper().setChangeAlphaWhenDisable(changeAlphaWhenDisable);
    }
}

在res/values里写一个属性attrs_base.xml

然后再应用的application的theme里面就可以写上