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Diffstat (limited to 'OpenPGP-Keychain/src/org/sufficientlysecure/keychain/ui/widget/DashboardLayout.java')
| -rw-r--r-- | OpenPGP-Keychain/src/org/sufficientlysecure/keychain/ui/widget/DashboardLayout.java | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/OpenPGP-Keychain/src/org/sufficientlysecure/keychain/ui/widget/DashboardLayout.java b/OpenPGP-Keychain/src/org/sufficientlysecure/keychain/ui/widget/DashboardLayout.java new file mode 100644 index 000000000..158a271bc --- /dev/null +++ b/OpenPGP-Keychain/src/org/sufficientlysecure/keychain/ui/widget/DashboardLayout.java @@ -0,0 +1,186 @@ +/* + * Copyright 2011 Google Inc. + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.sufficientlysecure.keychain.ui.widget; + +import android.content.Context; +import android.util.AttributeSet; +import android.view.View; +import android.view.ViewGroup; + +/** + * Custom layout that arranges children in a grid-like manner, optimizing for even horizontal and + * vertical whitespace. + */ +public class DashboardLayout extends ViewGroup { + private static final int UNEVEN_GRID_PENALTY_MULTIPLIER = 10; + + private int mMaxChildWidth = 0; + private int mMaxChildHeight = 0; + + public DashboardLayout(Context context) { + super(context, null); + } + + public DashboardLayout(Context context, AttributeSet attrs) { + super(context, attrs, 0); + } + + public DashboardLayout(Context context, AttributeSet attrs, int defStyle) { + super(context, attrs, defStyle); + } + + @Override + protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { + mMaxChildWidth = 0; + mMaxChildHeight = 0; + + // Measure once to find the maximum child size. + + int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec( + MeasureSpec.getSize(widthMeasureSpec), MeasureSpec.AT_MOST); + int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec( + MeasureSpec.getSize(heightMeasureSpec), MeasureSpec.AT_MOST); + + final int count = getChildCount(); + for (int i = 0; i < count; i++) { + final View child = getChildAt(i); + if (child.getVisibility() == GONE) { + continue; + } + + child.measure(childWidthMeasureSpec, childHeightMeasureSpec); + + mMaxChildWidth = Math.max(mMaxChildWidth, child.getMeasuredWidth()); + mMaxChildHeight = Math.max(mMaxChildHeight, child.getMeasuredHeight()); + } + + // Measure again for each child to be exactly the same size. + + childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(mMaxChildWidth, MeasureSpec.EXACTLY); + childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(mMaxChildHeight, MeasureSpec.EXACTLY); + + for (int i = 0; i < count; i++) { + final View child = getChildAt(i); + if (child.getVisibility() == GONE) { + continue; + } + + child.measure(childWidthMeasureSpec, childHeightMeasureSpec); + } + + setMeasuredDimension(resolveSize(mMaxChildWidth, widthMeasureSpec), + resolveSize(mMaxChildHeight, heightMeasureSpec)); + } + + @Override + protected void onLayout(boolean changed, int l, int t, int r, int b) { + int width = r - l; + int height = b - t; + + final int count = getChildCount(); + + // Calculate the number of visible children. + int visibleCount = 0; + for (int i = 0; i < count; i++) { + final View child = getChildAt(i); + if (child.getVisibility() == GONE) { + continue; + } + ++visibleCount; + } + + if (visibleCount == 0) { + return; + } + + // Calculate what number of rows and columns will optimize for even horizontal and + // vertical whitespace between items. Start with a 1 x N grid, then try 2 x N, and so on. + int bestSpaceDifference = Integer.MAX_VALUE; + int spaceDifference; + + // Horizontal and vertical space between items + int hSpace = 0; + int vSpace = 0; + + int cols = 1; + int rows; + + while (true) { + rows = (visibleCount - 1) / cols + 1; + + hSpace = ((width - mMaxChildWidth * cols) / (cols + 1)); + vSpace = ((height - mMaxChildHeight * rows) / (rows + 1)); + + spaceDifference = Math.abs(vSpace - hSpace); + if (rows * cols != visibleCount) { + spaceDifference *= UNEVEN_GRID_PENALTY_MULTIPLIER; + } else if (rows * mMaxChildHeight > height || cols * mMaxChildWidth > width) { + spaceDifference *= UNEVEN_GRID_PENALTY_MULTIPLIER; + } + + if (spaceDifference < bestSpaceDifference) { + // Found a better whitespace squareness/ratio + bestSpaceDifference = spaceDifference; + + // If we found a better whitespace squareness and there's only 1 row, this is + // the best we can do. + if (rows == 1) { + break; + } + } else { + // This is a worse whitespace ratio, use the previous value of cols and exit. + --cols; + rows = (visibleCount - 1) / cols + 1; + hSpace = ((width - mMaxChildWidth * cols) / (cols + 1)); + vSpace = ((height - mMaxChildHeight * rows) / (rows + 1)); + break; + } + + ++cols; + } + + // Lay out children based on calculated best-fit number of rows and cols. + + // If we chose a layout that has negative horizontal or vertical space, force it to zero. + hSpace = Math.max(0, hSpace); + vSpace = Math.max(0, vSpace); + + // Re-use width/height variables to be child width/height. + width = (width - hSpace * (cols + 1)) / cols; + height = (height - vSpace * (rows + 1)) / rows; + + int left, top; + int col, row; + int visibleIndex = 0; + for (int i = 0; i < count; i++) { + final View child = getChildAt(i); + if (child.getVisibility() == GONE) { + continue; + } + + row = visibleIndex / cols; + col = visibleIndex % cols; + + left = hSpace * (col + 1) + width * col; + top = vSpace * (row + 1) + height * row; + + child.layout(left, top, (hSpace == 0 && col == cols - 1) ? r : (left + width), + (vSpace == 0 && row == rows - 1) ? b : (top + height)); + ++visibleIndex; + } + } +}
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