/** * Measure the view and its content to determine the measured width and the * measured height. This method is invoked by {@link #measure(int, int)} and * should be overridden by subclasses to provide accurate and efficient * measurement of their contents. * </p> * * <p> * If this method is overridden, it is the subclass's responsibility to make * sure the measured height and width are at least the view's minimum height * and width ({@link #getSuggestedMinimumHeight()} and * {@link #getSuggestedMinimumWidth()}). * </p> * * @param widthMeasureSpec horizontal space requirements as imposed by the parent. * The requirements are encoded with * {@link android.view.View.MeasureSpec}. * @param heightMeasureSpec vertical space requirements as imposed by the parent. * The requirements are encoded with * {@link android.view.View.MeasureSpec}. * */ protectedvoidonMeasure(int widthMeasureSpec, int heightMeasureSpec) { setMeasuredDimension(getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec), getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec)); }
/** * Utility to return a default size. Uses the supplied size if the * MeasureSpec imposed no constraints. Will get larger if allowed * by the MeasureSpec. * * @param size Default size for this view * @param measureSpec Constraints imposed by the parent * @return The size this view should be. */ publicstaticintgetDefaultSize(int size, int measureSpec) { intresult= size; intspecMode= MeasureSpec.getMode(measureSpec); intspecSize= MeasureSpec.getSize(measureSpec);
switch (specMode) { case MeasureSpec.UNSPECIFIED: result = size; break; case MeasureSpec.AT_MOST: case MeasureSpec.EXACTLY: result = specSize; break; } return result; }
/** * Returns the suggested minimum width that the view should use. This * returns the maximum of the view's minimum width * and the background's minimum width * ({@link android.graphics.drawable.Drawable#getMinimumWidth()}). * <p> * When being used in {@link #onMeasure(int, int)}, the caller should still * ensure the returned width is within the requirements of the parent. * * @return The suggested minimum width of the view. */ protectedintgetSuggestedMinimumWidth() { return (mBackground == null) ? mMinWidth : max(mMinWidth, mBackground.getMinimumWidth()); }
/** * Returns the minimum width suggested by this Drawable. If a View uses this * Drawable as a background, it is suggested that the View use at least this * value for its width. (There will be some scenarios where this will not be * possible.) This value should INCLUDE any padding. * * @return The minimum width suggested by this Drawable. If this Drawable * doesn't have a suggested minimum width, 0 is returned. */ publicintgetMinimumWidth() { finalintintrinsicWidth= getIntrinsicWidth(); return intrinsicWidth > 0 ? intrinsicWidth : 0; } ... }
/** * Ask all of the children of this view to measure themselves, taking into * account both the MeasureSpec requirements for this view and its padding. * We skip children that are in the GONE state The heavy lifting is done in * getChildMeasureSpec. * * @param widthMeasureSpec The width requirements for this view * @param heightMeasureSpec The height requirements for this view */ protectedvoidmeasureChildren(int widthMeasureSpec, int heightMeasureSpec) { finalintsize= mChildrenCount; final View[] children = mChildren; for (inti=0; i < size; ++i) { finalViewchild= children[i]; if ((child.mViewFlags & VISIBILITY_MASK) != GONE) { measureChild(child, widthMeasureSpec, heightMeasureSpec); } } }
/** * Ask one of the children of this view to measure itself, taking into * account both the MeasureSpec requirements for this view and its padding. * The heavy lifting is done in getChildMeasureSpec. * * @param child The child to measure * @param parentWidthMeasureSpec The width requirements for this view * @param parentHeightMeasureSpec The height requirements for this view */ protectedvoidmeasureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { finalLayoutParamslp= child.getLayoutParams();
/** * Utility to reconcile a desired size and state, with constraints imposed * by a MeasureSpec. Will take the desired size, unless a different size * is imposed by the constraints. The returned value is a compound integer, * with the resolved size in the {@link #MEASURED_SIZE_MASK} bits and * optionally the bit {@link #MEASURED_STATE_TOO_SMALL} set if the * resulting size is smaller than the size the view wants to be. * * @param size How big the view wants to be. * @param measureSpec Constraints imposed by the parent. * @param childMeasuredState Size information bit mask for the view's * children. * @return Size information bit mask as defined by * {@link #MEASURED_SIZE_MASK} and * {@link #MEASURED_STATE_TOO_SMALL}. */ publicstaticintresolveSizeAndState(int size, int measureSpec, int childMeasuredState) { finalintspecMode= MeasureSpec.getMode(measureSpec); finalintspecSize= MeasureSpec.getSize(measureSpec); finalint result; switch (specMode) { case MeasureSpec.AT_MOST: if (specSize < size) { result = specSize | MEASURED_STATE_TOO_SMALL; } else { result = size; } break; case MeasureSpec.EXACTLY: result = specSize; break; case MeasureSpec.UNSPECIFIED: default: result = size; } return result | (childMeasuredState & MEASURED_STATE_MASK); }
