Don’t BB, look at the source code

getWidth()

  • The View class
     * Return the width of your view.
     *
     * @return The width of your view, in pixels.
     */
    public final int getWidth(a) {
        return mRight - mLeft;
    }

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  • So, what are mRight and mLeft?

  • Look at the source code

  /** * The distance in pixels from The left edge of this view's parent * to The left edge(edge) of this view.@hide} * The pixel distance from the current view's left edge to the parent view's left edge */
    protected int mLeft;
    /**
     * The distance in pixels from the left edge of this view's parent
     * to the right edge of this view.
     * {@hide} * Same with */
    protected int mRight;
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  • So, this is just a relative value obtained by adding and subtracting, not a real measured size;

getMeasuredWidth

* Like {@link #getMeasuredWidthAndState()}, but only returns the * raw width component (that is the result is masked by * {@link #MEASURED_SIZE_MASK}). * * @return The raw measured width of this view. * */ public Final int measuredWidth () {return mMeasuredWidth & MEASURED_SIZE_MASK; }Copy the code
  • There are two variables, one is mMeasuredWidth and one is MEASURED_SIZE_MASK

    /**
     * Bits of {@link #getMeasuredWidthAndState()} and
     * {@link# measuredwidthandState ()} that provide the actual (real) measured size. */
    public static final int MEASURED_SIZE_MASK = 0x00ffffff;
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MEASURED_SIZE_MASK = MEASURED_SIZE_MASK = MEASURED_SIZE_MASK = MEASURED_SIZE_MASK = MEASURED_SIZE_MASK = MEASURED_SIZE_MASK = MEASURED_SIZE_MASK = MEASURED_SIZE_MASK = MEASURED_SIZE_MASK = MEASURED_SIZE_MASK = MEASURED_SIZE_MASK = MEASURED_SIZE_MASK = MEASURED_SIZE_MASK = MEASURED_SIZE_MASK UNSPECIFIED, MeasureSpec.AT_MOST, MeasureSpec.EXACTLY, MeasureSpec encapsulates the mode and size with the makeMeasureSpec() method. The upper 2 bits are the measurement mode, and the lower 30 bits are the size of view.

How the value of mMeasuredWidth is set

  • OnMeasure ()—->setMeasuredDimension()—–>setMeasuredDimensionRaw()

  • Step 1: setMeasuredDimension();

  /**
     * <p>This method must be called by {@link#onMeasure(int, int)} to store the * measured width and measured height. Failing to do so will trigger an * exception at measurement </p> * This method must be called in onMeasure(int, int)@param measuredWidth The measured width of this view.  May be a complex
     * bit mask as defined by {@link #MEASURED_SIZE_MASK} and
     * {@link #MEASURED_STATE_TOO_SMALL}.
     * @param measuredHeight The measured height of this view.  May be a complex
     * bit mask as defined by {@link #MEASURED_SIZE_MASK} and
     * {@link #MEASURED_STATE_TOO_SMALL}.
     */
    protected final void setMeasuredDimension(int measuredWidth, int measuredHeight) {
        boolean optical = isLayoutModeOptical(this);
        if(optical ! = isLayoutModeOptical(mParent)) { Insets insets = getOpticalInsets();int opticalWidth  = insets.left + insets.right;
            int opticalHeight = insets.top  + insets.bottom;

            measuredWidth  += optical ? opticalWidth  : -opticalWidth;
            measuredHeight += optical ? opticalHeight : -opticalHeight;
        }
        // Set the original size of the view
        setMeasuredDimensionRaw(measuredWidth, measuredHeight);
    }

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Step 2: setMeasuredDimensionRaw();

    /**
    * 
     * Sets the measured dimension without extra processing for things like optical bounds.
     * Useful for reapplying consistent values that have already been cooked with adjustments
     * for optical bounds, etc. such as those from the measurement cache.
     *
     * @param measuredWidth The measured width of this view.  May be a complex
     * bit mask as defined by {@link #MEASURED_SIZE_MASK} and
     * {@link #MEASURED_STATE_TOO_SMALL}.
     * @param measuredHeight The measured height of this view.  May be a complex
     * bit mask as defined by {@link #MEASURED_SIZE_MASK} and
     * {@link #MEASURED_STATE_TOO_SMALL}.
     */
    private void setMeasuredDimensionRaw(int measuredWidth, int measuredHeight) {
        mMeasuredWidth = measuredWidth;
        mMeasuredHeight = measuredHeight;

        mPrivateFlags |= PFLAG_MEASURED_DIMENSION_SET;
    }

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  • Contains complex mask operations
  • MMeasuredWidth and mMeasuredHeight contain the true size of the view, as well as the measurement mode;
  • So, I getMeasuredWidth() takes the size after onMeasure();