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borderlayout 是 jframe 的默认布局类，相信大家都用过，swt没有提供这个java程序员非常熟悉的layout类。我们怎们来自己定义一个呢？首先要稍微了解一下layout的内部实现原理。
layouts 是一个容器用来对其子成员布局的一个算法，符合 strategy design pattern . 当 swt 打开一个 composite 时，会调用 composite 里的 layout.computesize() 计算 composite 的大小，然后再调 用 layout.layout() 设置子成员的位置和大小 . 如果需要， layout 会调用子成员的 getlayoutdata() 来获得单个子成员特别的属性。
computesize() 和 layout() 是抽象类 layout 的两个抽象方法。
要定义一个新的 layout ，也就是要定义一个 layout 的子类， 实现 computesize 和 layout. 对 borderlayout 来说，我们需要区分子控件是在哪个位置的 , 是 west 的，还是 east 的，还是 center 的，这个属性通过 control.setlayoutdata() 方法保存的各个控件里。
废话少说了，先看源代码
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-->public class borderlayout extends layout {
private control north;
private control south;
private control east;
private control west;
private control center;
protected void getcontrols(composite composite) {
control[] children = composite.getchildren();
for ( int i = 0 , n = children.length; i < n; i ++ ) {
control child = children[i];
borderdata borderdata = (borderdata) child.getlayoutdata();
if (borderdata == borderdata.north)
north = child;
else if (borderdata == borderdata.south)
south = child;
else if (borderdata == borderdata.east)
east = child;
else if (borderdata == borderdata.west)
west = child;
else
center = child;
}
}
}
control的layout data可以用control.setlayoutdata()方法设定, 所以getcontrol()方法找着各个控件的相应位置。
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--> protected point computesize(composite composite, int whint, int hhint,
boolean flushcache) {
getcontrols(composite);
int width = 0 , height = 0 ;
width += west == null ? 0 : getsize(west, flushcache).x;
width += east == null ? 0 : getsize(east, flushcache).x;
width += center == null ? 0 : getsize(center, flushcache).x;
if (north != null ) {
point pt = getsize(north, flushcache);
width = math.max(width, pt.x);
}
if (south != null ) {
point pt = getsize(south, flushcache);
width = math.max(width, pt.x);
}
height += north == null ? 0 : getsize(north, flushcache).y;
height += south == null ? 0 : getsize(south, flushcache).y;
int heightother = center == null ? 0 : getsize(center, flushcache).y;
if (west != null ) {
point pt = getsize(west, flushcache);
heightother = math.max(heightother, pt.y);
}
if (east != null ) {
point pt = getsize(east, flushcache);
heightother = math.max(heightother, pt.y);
}
height += heightother;
return new point(math.max(width, whint), math.max(height, hhint));
}
computesize计算composite所需的大小。
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--> protected void layout(composite composite, boolean flushcache) {
getcontrols(composite);
rectangle rect = composite.getclientarea();
int left = rect.x, right = rect.width, top = rect.y, bottom = rect.height;
if (north != null ) {
point pt = getsize(north, flushcache);
north.setbounds(left, top, rect.width, pt.y);
top += pt.y;
}
if (south != null ) {
point pt = getsize(south, flushcache);
south.setbounds(left, rect.height - pt.y, rect.width, pt.y);
bottom -= pt.y;
}
if (east != null ) {
point pt = getsize(east, flushcache);
east.setbounds(rect.width - pt.x, top, pt.x, (bottom - top));
right -= pt.x;
}
if (west != null ) {
point pt = getsize(west, flushcache);
west.setbounds(left, top, pt.x, (bottom - top));
left += pt.x;
}
if (center != null ) {
center.setbounds(left, top, (right - left), (bottom - top));
}
}
而layout方法让控件们各归其位。整个布局调用是回归的。 完整的代码borderlayout.rar
control的layout data可以用control.setlayoutdata()方法设定, 所以getcontrol()方法找着各个控件的相应位置。
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--> protected point computesize(composite composite, int whint, int hhint,
boolean flushcache) {
getcontrols(composite);
int width = 0 , height = 0 ;
width += west == null ? 0 : getsize(west, flushcache).x;
width += east == null ? 0 : getsize(east, flushcache).x;
width += center == null ? 0 : getsize(center, flushcache).x;
if (north != null ) {
point pt = getsize(north, flushcache);
width = math.max(width, pt.x);
}
if (south != null ) {
point pt = getsize(south, flushcache);
width = math.max(width, pt.x);
}
height += north == null ? 0 : getsize(north, flushcache).y;
height += south == null ? 0 : getsize(south, flushcache).y;
int heightother = center == null ? 0 : getsize(center, flushcache).y;
if (west != null ) {
point pt = getsize(west, flushcache);
heightother = math.max(heightother, pt.y);
}
if (east != null ) {
point pt = getsize(east, flushcache);
heightother = math.max(heightother, pt.y);
}
height += heightother;
return new point(math.max(width, whint), math.max(height, hhint));
}
computesize计算composite所需的大小。
code highlighting produced by actipro codehighlighter (freeware)
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--> protected void layout(composite composite, boolean flushcache) {
getcontrols(composite);
rectangle rect = composite.getclientarea();
int left = rect.x, right = rect.width, top = rect.y, bottom = rect.height;
if (north != null ) {
point pt = getsize(north, flushcache);
north.setbounds(left, top, rect.width, pt.y);
top += pt.y;
}
if (south != null ) {
point pt = getsize(south, flushcache);
south.setbounds(left, rect.height - pt.y, rect.width, pt.y);
bottom -= pt.y;
}
if (east != null ) {
point pt = getsize(east, flushcache);
east.setbounds(rect.width - pt.x, top, pt.x, (bottom - top));
right -= pt.x;
}
if (west != null ) {
point pt = getsize(west, flushcache);
west.setbounds(left, top, pt.x, (bottom - top));
left += pt.x;
}
if (center != null ) {
center.setbounds(left, top, (right - left), (bottom - top));
}
}
而layout方法让控件们各归其位。整个布局调用是回归的。 完整的代码borderlayout.rar
control的layout data可以用control.setlayoutdata()方法设定, 所以getcontrol()方法找着各个控件的相应位置。
code highlighting produced by actipro codehighlighter (freeware)
http://www.codehighlighter.com/
--> protected point computesize(composite composite, int whint, int hhint,
boolean flushcache) {
getcontrols(composite);
int width = 0 , height = 0 ;
width += west == null ? 0 : getsize(west, flushcache).x;
width += east == null ? 0 : getsize(east, flushcache).x;
width += center == null ? 0 : getsize(center, flushcache).x;
if (north != null ) {
point pt = getsize(north, flushcache);
width = math.max(width, pt.x);
}
if (south != null ) {
point pt = getsize(south, flushcache);
width = math.max(width, pt.x);
}
height += north == null ? 0 : getsize(north, flushcache).y;
height += south == null ? 0 : getsize(south, flushcache).y;
int heightother = center == null ? 0 : getsize(center, flushcache).y;
if (west != null ) {
point pt = getsize(west, flushcache);
heightother = math.max(heightother, pt.y);
}
if (east != null ) {
point pt = getsize(east, flushcache);
heightother = math.max(heightother, pt.y);
}
height += heightother;
return new point(math.max(width, whint), math.max(height, hhint));
}
computesize计算composite所需的大小。
code highlighting produced by actipro codehighlighter (freeware)
http://www.codehighlighter.com/
--> protected void layout(composite composite, boolean flushcache) {
getcontrols(composite);
rectangle rect = composite.getclientarea();
int left = rect.x, right = rect.width, top = rect.y, bottom = rect.height;
if (north != null ) {
point pt = getsize(north, flushcache);
north.setbounds(left, top, rect.width, pt.y);
top += pt.y;
}
if (south != null ) {
point pt = getsize(south, flushcache);
south.setbounds(left, rect.height - pt.y, rect.width, pt.y);
bottom -= pt.y;
}
if (east != null ) {
point pt = getsize(east, flushcache);
east.setbounds(rect.width - pt.x, top, pt.x, (bottom - top));
right -= pt.x;
}
if (west != null ) {
point pt = getsize(west, flushcache);
west.setbounds(left, top, pt.x, (bottom - top));
left += pt.x;
}
if (center != null ) {
center.setbounds(left, top, (right - left), (bottom - top));
}
}
而layout方法让控件们各归其位。整个布局调用是回归的。 完整的代码borderlayout.rar
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