界面无小事(五):自定义TextView

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="MyTextView">
        <attr name="text" format="string" />
        <attr name="color" format="color" />
        <attr name="size" format="dimension" />
    </declare-styleable>
</resources>

xmlns:app="http://schemas.android.com/apk/res-auto"

<com.so.mytextview.ui.view.MyTextView
    android:id="@+id/mtv_test"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerInParent="true"
    app:color="@color/colorAccent"
    app:size="60sp"
    app:text="hello world" />

public MyTextView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);

    init(context, attrs);
}

private void init(Context context, AttributeSet attrs) {
    // 获取自定义属性
    TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.MyTextView);

    mSize = ta.getDimension(R.styleable.MyTextView_size, 16);
    mText = ta.getString(R.styleable.MyTextView_text);
    mColor = ta.getColor(R.styleable.MyTextView_color, Color.BLACK);

    ta.recycle();

    // 设置画笔
    mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    mPaint.setTextSize(mSize);

    // 设置背景颜色
    mBkColor = Color.BLUE;
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);

    int width = 0;
    int height = 0;

    int specMode = MeasureSpec.getMode(widthMeasureSpec);
    int specSize = MeasureSpec.getSize(widthMeasureSpec);

    switch (specMode) {
        case MeasureSpec.EXACTLY:
            width = getPaddingLeft() + getPaddingRight() + specSize;
            break;

        case MeasureSpec.AT_MOST:
        case MeasureSpec.UNSPECIFIED:
            width = (int) (getPaddingLeft() + getPaddingRight()
                    + mPaint.measureText(mText));
            break;
    }

    specMode = MeasureSpec.getMode(heightMeasureSpec);
    specSize = MeasureSpec.getSize(heightMeasureSpec);

    switch (specMode) {
        case MeasureSpec.EXACTLY:
            height = getPaddingTop() + getPaddingBottom() + specSize;
            break;

        case MeasureSpec.AT_MOST:
        case MeasureSpec.UNSPECIFIED:
            Paint.FontMetrics fmi = mPaint.getFontMetrics();
            float textHeight = Math.abs(fmi.bottom - fmi.top);
            height = (int) (getPaddingTop() + getPaddingBottom() + textHeight);
            break;
    }

    setMeasuredDimension(width, height);
}

/**
 * 依据颜色值获取rgb值
 *
 * @param color 颜色值
 * @return rgb值
 */
public int[] setColor(int color) {
    int[] rgb = new int[3];
    rgb[0] = (color & 0x00ff0000) >> 16;
    rgb[1] = (color & 0x0000ff00) >> 8;
    rgb[2] = (color & 0x000000ff);
    return rgb;
}

/**
 * sp转px
 */
public static int sp2px(float spVal) {
    return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP,
            spVal, getContext().getResources().getDisplayMetrics());
}

/**
 * px转sp
 */
public static float px2sp(float pxVal) {
    return (pxVal / getContext().getResources().getDisplayMetrics().scaledDensity);
}