layout_margintop 百分比_layout marginleft_layout marginend用法(5)

所以上面代码的意思就是通过对每个子View调用getLayoutParams方法，然后从该LayoutParams中获取到它的PercentLayoutInfo属性，然后再调用PercentLayoutInfo.fillMarginLayoutParams()方法。

那我们继续看一下PercentLayoutInfo.fillMarginLayoutParams()方法的实现，该方法是根据百分比去设置尺寸和margin:

/**
         * Fills {@code ViewGroup.MarginLayoutParams} dimensions and margins based on percentage
         * values.
         */
        public void fillMarginLayoutParams(View view, ViewGroup.MarginLayoutParams params,
                int widthHint, int heightHint) {
            // 根据百分比值设置View的尺寸
            fillLayoutParams(params, widthHint, heightHint);

            // 从注释中就能知道，fillLayoutParams是计算尺寸，那下面这部分就是处理margin了
            // mPreservedParams来记录原始的margin值
            // Preserve the original margins, so we can restore them after the measure step.
            mPreservedParams.leftMargin = params.leftMargin;
            mPreservedParams.topMargin = params.topMargin;
            mPreservedParams.rightMargin = params.rightMargin;
            mPreservedParams.bottomMargin = params.bottomMargin;
            MarginLayoutParamsCompat.setMarginStart(mPreservedParams,
                    MarginLayoutParamsCompat.getMarginStart(params));
            MarginLayoutParamsCompat.setMarginEnd(mPreservedParams,
                    MarginLayoutParamsCompat.getMarginEnd(params));

            if (leftMarginPercent >= 0) {
                params.leftMargin = (int) (widthHint * leftMarginPercent);
            }
            if (topMarginPercent >= 0) {
                params.topMargin = (int) (heightHint * topMarginPercent);
            }
            if (rightMarginPercent >= 0) {
                params.rightMargin = (int) (widthHint * rightMarginPercent);
            }
            if (bottomMarginPercent >= 0) {
                params.bottomMargin = (int) (heightHint * bottomMarginPercent);
            }
            boolean shouldResolveLayoutDirection = false;
            if (startMarginPercent >= 0) {
                MarginLayoutParamsCompat.setMarginStart(params,
                        (int) (widthHint * startMarginPercent));
                shouldResolveLayoutDirection = true;
            }
            if (endMarginPercent >= 0) {
                MarginLayoutParamsCompat.setMarginEnd(params,
                        (int) (widthHint * endMarginPercent));
                shouldResolveLayoutDirection = true;
            }
            if (shouldResolveLayoutDirection && (view != null)) {
                // Force the resolve pass so that start / end margins are propagated to the
                // matching left / right fields
                MarginLayoutParamsCompat.resolveLayoutDirection(params,
                        ViewCompat.getLayoutDirection(view));
            }
            if (Log.isLoggable(TAG, Log.DEBUG)) {
                Log.d(TAG, "after fillMarginLayoutParams: (" + params.width + ", " + params.height
                        + ")");
            }
        }

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