根据 Google 设计模式，我一直在使用 Google 在 Google IO 应用程序中使用的DashboardLayout.java文件来实现仪表板布局。这在使用按钮时工作正常，但是一旦我添加自定义视图，由 DashboardLayout.java 文件生成的网格视图就会分崩离析：
在没有自定义视图的情况下工作：
不使用自定义视图：
自定义视图的代码是：
public class Countdown extends View {
int viewWidth;
int viewHeight;
Paint textPaint;
Paint titlePaint;
Paint labelPaint;
Paint rectanglePaint;
PeriodFormatter daysFormatter;
PeriodFormatter hoursFormatter;
PeriodFormatter minutesFormatter;
PeriodFormatter secondsFormatter;
DateTimeZone frenchTimeZone;
DateTime expiry;
Context ctx;
static int[] rectWidth;
static int[] rectHeight;
boolean flag = true;
public Countdown(Context context) {
super(context);
ctx = context;
init();
}
public Countdown(Context context, AttributeSet attrs) {
super(context, attrs);
ctx = context;
init();
}
public Countdown(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
ctx = context;
init();
}
private void init()
{
rectWidth = new int[]{0,0,0,0};
rectHeight = new int[]{0,0,0,0};
textPaint = new Paint();
titlePaint = new Paint();
labelPaint = new Paint();
rectanglePaint = new Paint();
frenchTimeZone = DateTimeZone.forID("Europe/Paris");
expiry = new DateTime(2012, 6, 17, 8, 30, frenchTimeZone);
//setup paints
//turn antialiasing on
textPaint.setAntiAlias(true);
int timerScaledSize = getResources().getDimensionPixelSize(R.dimen.text_size_dashboard_timer);
textPaint.setTextSize(timerScaledSize);
textPaint.setColor(Color.WHITE);
textPaint.setTextAlign(Align.CENTER);
labelPaint.setAntiAlias(true);
int labelScaledSize = getResources().getDimensionPixelSize(R.dimen.text_size_dashboard_timer_boxes_label);
labelPaint.setTextSize(labelScaledSize);
labelPaint.setColor(Color.BLACK);
labelPaint.setTextAlign(Align.CENTER);
labelPaint.setTypeface(Typeface.defaultFromStyle(Typeface.BOLD));
titlePaint.setAntiAlias(true);
int titleScaledSize = getResources().getDimensionPixelSize(R.dimen.text_size_dashboard_title);
titlePaint.setTextSize(titleScaledSize);
titlePaint.setTypeface(Typeface.defaultFromStyle(Typeface.BOLD));
titlePaint.setColor(Color.WHITE);
rectanglePaint.setAntiAlias(true);
daysFormatter = new PeriodFormatterBuilder()
.printZeroIfSupported()
.minimumPrintedDigits(2)
.appendDays()
.toFormatter();
hoursFormatter = new PeriodFormatterBuilder()
.printZeroIfSupported()
.minimumPrintedDigits(2)
.appendHours()
.toFormatter();
minutesFormatter = new PeriodFormatterBuilder()
.printZeroIfSupported()
.minimumPrintedDigits(2)
.appendMinutes()
.toFormatter();
secondsFormatter = new PeriodFormatterBuilder()
.printZeroIfSupported()
.minimumPrintedDigits(2)
.appendSeconds()
.toFormatter();
}
@Override
public void onDraw(Canvas canvas)
{
DateTime now = new DateTime();
Period p = new Period(now, expiry, PeriodType.dayTime());
canvas.drawColor(Color.TRANSPARENT);
if(flag)
{
// To ensure the rectangles will be wide enough for all numbers we cheat and initially set the width based upon 00.
flag = false;
drawTextRectangle(0, textPaint, labelPaint, canvas, "00", "", scaleForDensity(20, ctx), scaleForDensity(33, ctx));
drawTextRectangle(1, textPaint, labelPaint, canvas, "00", "", scaleForDensity(53, ctx), scaleForDensity(33, ctx));
drawTextRectangle(2, textPaint, labelPaint, canvas, "00", "", scaleForDensity(87, ctx), scaleForDensity(33, ctx));
drawTextRectangle(3, textPaint, labelPaint, canvas, "00", "", scaleForDensity(120, ctx), scaleForDensity(33, ctx));
}
String title = "Countdown";
float textWidth = titlePaint.measureText(title);
float titleStartPositionX = (viewWidth - textWidth) / 2;
canvas.drawText(title, titleStartPositionX, viewHeight - scaleForDensity(5, ctx), titlePaint);
Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.dashboard_counter);
canvas.drawBitmap(bitmap, 0, 0, null);
drawTextRectangle(0, textPaint, labelPaint, canvas, daysFormatter.print(p), "DAYS", scaleForDensity(20, ctx), scaleForDensity(33, ctx));
drawTextRectangle(1, textPaint, labelPaint, canvas, hoursFormatter.print(p), "HRS", scaleForDensity(53, ctx), scaleForDensity(33, ctx));
drawTextRectangle(2, textPaint, labelPaint, canvas, minutesFormatter.print(p), "MINS", scaleForDensity(87, ctx), scaleForDensity(33, ctx));
drawTextRectangle(3, textPaint, labelPaint, canvas, secondsFormatter.print(p), "SECS", scaleForDensity(120, ctx), scaleForDensity(33, ctx));
invalidate();
}
private void drawTextRectangle(int index, Paint paint, Paint labelPaint, Canvas canvas, String text, String label, float x, float y) {
paint.setTextAlign(Align.CENTER);
Rect bounds = new Rect();
bounds = new Rect();
paint.getTextBounds(text, 0, text.length(), bounds);
if(rectWidth[index] == 0)
{
rectWidth[index] = Math.abs(bounds.right - bounds.left);
rectWidth[index] += scaleForDensity(5, ctx);
}
if(rectHeight[index] == 0)
{
rectHeight[index] = Math.abs(bounds.bottom - bounds.top);
rectHeight[index] += scaleForDensity(5, ctx);
}
bounds.left = (int) (x - (rectWidth[index] / 2));
bounds.top = (int) (y - rectHeight[index]);
bounds.right = bounds.left + rectWidth[index];
bounds.bottom = (int) (bounds.top + rectHeight[index] + scaleForDensity(7, ctx));
Paint rectanglePaint = new Paint();
rectanglePaint.setAntiAlias(true);
rectanglePaint.setShader(new LinearGradient(bounds.centerX(), bounds.top, bounds.centerX(), bounds.bottom, 0xff8ed8f8, 0xff207d94, TileMode.MIRROR));
RectF boundsF = new RectF(bounds);
canvas.drawRoundRect(boundsF, 2f, 2f, rectanglePaint);
canvas.drawText(text, x, y, paint);
canvas.drawText(label, x, y + rectHeight[index], labelPaint);
}
public float scaleForDensity(float px, Context context)
{
Resources resources = context.getResources();
DisplayMetrics metrics = resources.getDisplayMetrics();
return px * metrics.density + .5f;
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
{
int width = measureWidth(widthMeasureSpec);
int height = measureHeight(heightMeasureSpec, widthMeasureSpec);
viewWidth = width;
viewHeight = height;
setMeasuredDimension(width, height);
}
private int measureWidth(int measureSpec)
{
int result = 0;
int specMode = MeasureSpec.getMode(measureSpec);
int specSize = MeasureSpec.getSize(measureSpec);
if (specMode == MeasureSpec.EXACTLY) {
// We were told how big to be
result = specSize;
} else {
// Measure the text
result = measureSpec;
if (specMode == MeasureSpec.AT_MOST) {
// Respect AT_MOST value if that was what is called for by measureSpec
result = Math.min(result, specSize);
}
}
return result;
}
private int measureHeight(int measureSpecHeight, int measureSpecWidth) {
int result = 0;
int specMode = MeasureSpec.getMode(measureSpecHeight);
int specSize = MeasureSpec.getSize(measureSpecHeight);
if (specMode == MeasureSpec.EXACTLY) {
// We were told how big to be
result = specSize;
} else {
// Measure the text (beware: ascent is a negative number)
result = viewWidth;
/*if (specMode == MeasureSpec.AT_MOST) {
// Respect AT_MOST value if that was what is called for by measureSpec
result = Math.min(result, specSize);
}*/
}
return result;
}
}
我正在使用的 DashboardLayout 代码：
/**
* 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;
boolean run = true;
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) {
if(run)
{
run = false;
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(widthMeasureSpec), 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;
}
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;
}
}
}
最后但并非最不重要的布局：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TextView
style="@style/HeaderTextView"
android:text="@string/header_dashboard" />
<View
android:layout_width="fill_parent"
android:layout_height="@dimen/content_divider_height"
android:layout_marginLeft="@dimen/content_divider_margin"
android:layout_marginRight="@dimen/content_divider_margin"
android:background="@color/content_divider_colour" />
<com.a.b.ui.DashboardLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent"
style="@style/Container">
<!-- The custom view that once un-commented cause the problem -->
<!-- <com.a.b.widget.Countdown
style="@style/DashboardButton" /> -->
<Button android:id="@+id/home_btn_news"
style="@style/DashboardButton"
android:text="A"
android:drawableTop="@drawable/dashboard_counter" />
<Button android:id="@+id/home_btn_feed"
style="@style/DashboardButton"
android:text="B"
android:drawableTop="@drawable/dashboard_counter" />
<Button android:id="@+id/home_btn_guide"
style="@style/DashboardButton"
android:text="C"
android:drawableTop="@drawable/dashboard_counter" />
<Button android:id="@+id/home_btn_sessions"
style="@style/DashboardButton"
android:text="D"
android:drawableTop="@drawable/dashboard_counter" />
<Button android:id="@+id/home_btn_events"
style="@style/DashboardButton"
android:text="E"
android:drawableTop="@drawable/dashboard_counter" />
</com.a.b.ui.DashboardLayout>
</LinearLayout>
对发布的代码量表示歉意，但我希望它可以更容易地查看问题。