问题描述
使用文档中的这个 MWE:
CronJob
如何让下拉列表打开而不是关闭?我正在尝试将列表放在屏幕的下边缘。我在文档中找不到选项。
解决方法
因为 ControlP5 使用 Java 泛型继承实际上在这种情况下非常棘手,应该覆盖 ScrollableListView
的 display()
方法:
ScrollableList extends Controller< ScrollableList >
- 在java中,一个类可以子类化单个类,而不是多个类,因此像
PopUpScrollableList
这样的自定义子类将继承Controller< ScrollableList >
,而不是Controller< PopUpScrollableList >
- 在
ScrollableListView
的display()
中访问了一堆属于ScrollableList
的属性,它们是private
或protected
TLDR;
@laancelot 建议克隆库,直接修改 ScrollableListView
的 display()
方法并重新编译库,与子类化和自定义滚动列表相比,这听起来更容易。
话虽如此,对于初学者来说,设置 IDE 和编译 Java 库可能不是最友好的事情,因此我可以推荐一个hacky 解决方法:只需移动列表的 y 位置,使其看起来在上方而不是下方:
import controlP5.*;
import java.util.*;
ControlP5 cp5;
ScrollableList list;
int listX = 100;
int listY = 100;
int listWidth = 200;
int listHeight = 100;
int barHeight = 20;
void setup() {
size(400,400);
cp5 = new ControlP5(this);
List l = Arrays.asList("a","b","c","d","e","f","g","h");
/* add a ScrollableList,by default it behaves like a DropdownList */
list = cp5.addScrollableList("dropdown")
.setPosition(listX,listY)
.setSize(listWidth,listHeight)
.setBarHeight(barHeight)
.setItemHeight(20)
.addItems(l)
// .setType(ScrollableList.LIST) // currently supported DROPDOWN and LIST
;
}
void draw() {
// hack: shift the list up when it's open
if(list.isOpen()){
list.setPosition(listX,listY - listHeight + barHeight);
}else{
list.setPosition(listX,listY);
}
background(240);
}
它在视觉上并不完美,可能是一种潜在的令人尴尬的用户体验,但它是使用 ControlP5 实现此自定义行为的最简单选项。
或者,值得考虑自定义不同的 UI 库或编写自定义列表。
为了论证起见,这里是Guido library列表示例的修改版本:
/**
* A list
*
*
* Make sure to try your scroll wheel!
*/
import de.bezier.guido.*;
Listbox listbox;
SimpleButton button;
Object lastItemClicked;
void setup ()
{
size(400,400);
// make the manager
Interactive.make( this );
// create a list box
listbox = new Listbox( 20,30,width-40,height-80 );
for ( int i = 0,r = int(10+random(100)); i < r; i++ )
{
listbox.addItem( "Item " + i );
}
listbox.visible = false;
// create button
button = new SimpleButton("pop-up list",20,350,24 );
}
void draw ()
{
background( 20 );
listbox.visible = button.on;
if ( lastItemClicked != null )
{
fill( 255 );
text( "Clicked " + lastItemClicked.toString(),20 );
}
}
public void itemClicked ( int i,Object item )
{
lastItemClicked = item;
}
public class Listbox
{
float x,y,width,height;
ArrayList items;
int itemHeight = 20;
int listStartAt = 0;
int hoverItem = -1;
float valueY = 0;
boolean hasSlider = false;
boolean visible = true;
Listbox ( float xx,float yy,float ww,float hh )
{
x = xx; y = yy;
valueY = y;
width = ww; height = hh;
// register it
Interactive.add( this );
}
public void addItem ( String item )
{
if ( items == null ) items = new ArrayList();
items.add( item );
hasSlider = items.size() * itemHeight > height;
}
public void mouseMoved ( float mx,float my )
{
if(!visible){
return;
}
if ( hasSlider && mx > width-20 ) return;
hoverItem = listStartAt + int((my-y) / itemHeight);
}
public void mouseExited ( float mx,float my )
{
if(!visible){
return;
}
hoverItem = -1;
}
// called from manager
void mouseDragged ( float mx,float my )
{
if(!visible){
return;
}
if ( !hasSlider ) return;
if ( mx < x+width-20 ) return;
valueY = my-10;
valueY = constrain( valueY,y+height-20 );
update();
}
// called from manager
void mouseScrolled ( float step )
{
if(!visible){
return;
}
valueY += step;
valueY = constrain( valueY,y+height-20 );
update();
}
void update ()
{
if(!visible){
return;
}
float totalHeight = items.size() * itemHeight;
float itemsInView = height / itemHeight;
float listOffset = map( valueY,y+height-20,totalHeight-height );
listStartAt = int( listOffset / itemHeight );
}
public void mousePressed ( float mx,float my )
{
if(!visible){
return;
}
if ( hasSlider && mx > width-20 ) return;
int item = listStartAt + int( (my-y) / itemHeight);
itemClicked( item,items.get(item) );
}
void draw ()
{
if(!visible){
return;
}
noStroke();
fill( 100 );
rect( x,this.width,this.height );
if ( items != null )
{
for ( int i = 0; i < int(height/itemHeight) && i < items.size(); i++ )
{
stroke( 80 );
fill( (i+listStartAt) == hoverItem ? 200 : 120 );
rect( x,y + (i*itemHeight),itemHeight );
noStroke();
fill( 0 );
text( items.get(i+listStartAt).toString(),x+5,y+(i+1)*itemHeight-5 );
}
}
if ( hasSlider )
{
stroke( 80 );
fill( 100 );
rect( x+width-20,height );
fill( 120 );
rect( x+width-20,valueY,20 );
}
}
}
public class SimpleButton
{
float x,height;
boolean on;
String label = "";
SimpleButton ( float xx,float w,float h )
{
x = xx; y = yy; width = w; height = h;
Interactive.add( this ); // register it with the manager
}
SimpleButton ( String label,float xx,float h )
{
this(xx,yy,w,h);
this.label = label;
}
// called by manager
void mousePressed ()
{
on = !on;
}
void draw ()
{
if ( on ) fill( 200 );
else fill( 100 );
rect(x,height);
if ( on ) fill( 100 );
else fill( 200 );
text(label,x + 10,y + this.height * 0.65);
}
}
草图中的代码更加冗长,但可以移至单独的 GUI 选项卡。 希望因为它更简单,所以可以比 ControlP5 更容易地操作自定义行为。