画布的宽度是否有限制 [英] Is there a limit for the width of a canvas

问题描述

画布属性width的值是否有限制？

在下面的示例中，我在ScrolledWindow中创建一个Canvas。 p>

 ＃包
 package require BWidget 
 
＃Mainframe 
 set mfr [MainFrame。 mfr -textvariableTest] 
 pack $ mfr -fill both -expand yes 
 
＃创建一个带有两个窗格的窗口
 set pw1 [PanedWindow [$ mfr getframe]。 pw1-left] 
 set pat [$ pw1 add -minsize 200] 
 set pai [$ pw1 add -minsize 200] 
 pack $ pw1 -fill both -expand yes -anchor nw 
 
＃为每个窗格创建一个框架
 set tft [TitleFrame $ pat.tft -textScrollable Canvas] 
 set tfi [TitleFrame $ pai.tfi -textInformations ] 
 pack $ tft -fill both -expand yes -anchor nw 
 pack $ tfi -fill both -expand yes -anchor nw 
 
＃在ScrolledWindow内创建一个画布
 set swt [scrollableFrame b $ b $ swt setwidget $ sft 
 set tab [canvas [$ sft getframe] .tab -width 50000 -height 200 -background black] 
＃在画布上绘制一条水平线
 $ tab create line 0 100 50000 100 -width 1 -fill white 
 
 pack $ tab -fill both -expand yes -anchor nw 
 pack $ swt -fill both -expand yes -anchor nw 
 
＃为第二个窗格创建一个ScrolledWindow 
 set swl [ScrolledWindow [$ tfi getframe] .swl -relief sunken -borderwidth 2 -scrollbar vertical -auto both] 
 pack $ swl -expand yes -fill both 
 
＃显示窗口管理器
 wm minsize。 600 350 
 wm deiconify。 
 wm协议。 WM_DELETE_WINDOW {exit} 
 bind。 < Control-q> {out} 
  

在本例中，我为画布使用了50 000当我使用滚动条时，画布的黑盒子结束。同样的问题也会影响在画布上绘制的水平线。

我错过了什么吗？
画布的width属性是否有已知的限制？

感谢您的帮助

short c>的限制），那么事情会变得有点古怪。特别是在渲染层（和绝对不使画布视口的大小！然而，底层的画布模型使用IEEE double s来存储坐标，所以没有理由为什么你不能远离那些东西。

这是所有的X11的遗产，它使用16位的值在​​很多关键结构中的坐标和尺寸。改变这在逻辑上很容易，在实践中的很多工作（假设是在所有地方）。

Is there a limit for the value of the attribute "width" of a canvas ?

In the following example, I create a Canvas in a ScrolledWindow.

# Packages
package require BWidget

# Mainframe
set mfr [MainFrame .mfr -textvariable "Test"]
pack $mfr -fill both -expand yes

# Create a Paned Window with two panes
set pw1 [PanedWindow [$mfr getframe].pw1 -side left]
set pat [$pw1 add -minsize 200]
set pai [$pw1 add -minsize 200]
pack $pw1 -fill both -expand yes -anchor nw

# Create a frame for each pane
set tft [TitleFrame $pat.tft -text "Scrollable Canvas"]
set tfi [TitleFrame $pai.tfi -text "Informations"]
pack $tft -fill both -expand yes -anchor nw
pack $tfi -fill both -expand yes -anchor nw

# Create a canvas inside a ScrolledWindow for the first pane
set swt [ScrolledWindow [$tft getframe].swt -relief sunken -borderwidth 2 -scrollbar horizontal -auto none]
set sft [ScrollableFrame $swt.sft -width 50000 -height 200]
$swt setwidget $sft
set tab [canvas [$sft getframe].tab -width 50000 -height 200 -background black]
# Draw an horizontal line on the canvas
$tab create line 0 100 50000 100 -width 1 -fill white

pack $tab -fill both -expand yes -anchor nw
pack $swt -fill both -expand yes -anchor nw

# Create a ScrolledWindow for the second pane
set swl [ScrolledWindow [$tfi getframe].swl -relief sunken -borderwidth 2 -scrollbar vertical -auto both]
pack $swl -expand yes -fill both

# Display the window manager
wm minsize . 600 350
wm deiconify .
wm protocol . WM_DELETE_WINDOW {exit}
bind . <Control-q> {exit}

In this example, I used a width of "50 000" for the canvas, but when I use the scrollbar the black box of the canvas ends before. The same issue also affects the horizontal line which is drawn on the canvas.

Do I missed something ? Is there a known limit for the "width" attribute of the canvas ?

Thanks for your help

解决方案

Things get a bit funky if you make them larger than 32,000 (strictly 32767, the limit of a signed C short) particularly at the rendering layer (and definitely don't make the canvas viewport that size!). However, the underlying canvas model uses IEEE doubles to store the coordinates, so there's no reason why you couldn't have things go off that far. You just must keep the size of individual objects down.

This is all a legacy of X11, which uses 16-bit values for coordinates and dimensions in quite a few key structures. Changing this is both logically easy and a lot of work in practice (the assumptions are all over the place).

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