Tk中用Canvas绘图，Scrollbar不起作用

hztj2005

下面代码，Scrollbar出现，但不起作用，请教：

1. <p>use Tk;
   
2. use utf8;
   
3. $mw = MainWindow->new( );
   
4. $mw->geometry("300x100");#1368
   
5. $mw->title("模式关系网");#
   
6. $mw->title("One Scrollbar/Three Listboxes");
   
7. $mw->Button(-text => "Exit",
   
8.             -command => sub { exit })->pack(-side => 'bottom');
   
9. 
   
10. $scltest = $mw->Scrollbar( );
    
11. 
    
12. $canvas =  $mw->Canvas();
    
13. 
    
14. 
    
15. sub scroll_canvas {
    
16.   my ($scltest, $canvas,  @args) = @_;
    
17.   $scltest->set(@args);
    
18. 
    
19. }
    
20. 
    
21. 
    
22. $canvas->configure(-yscrollcommand => [ \&scroll_canvas, $scltest,
    
23.                                        $canvas, ]);
    
24. 
    
25. 
    
26. # Configure the Scrollbar to scroll each Listbox
    
27. $scltest->configure(-command => ['yview' => $canvas]);
    
28. 
    
29. # Pack the Scrollbar and Listboxes
    
30. 
    
31. $scltest->pack(-side => 'left', -fill => 'y');
    
32. 
    
33. $canvas->pack(-side => 'left');
    
34. 
    
35. my $bt102 = $canvas->Button(-text => "下个方法",
    
36.                         -command => \&printinfo);
    
37. 
    
38. my $id102 = $canvas->createWindow(36,30, -window =>$bt102);
    
39. 
    
40. my $bt103 = $canvas->Button(-text => "上个方法",
    
41.                         -command => \&printinfo);
    
42. 
    
43. 
    
44. my $id104 = $canvas->createWindow(36,200, -window =>$bt104);
    
45. 
    
46. 
    
47. my $bt105 = $canvas->createLine( 30,40,400,400, -fill =>  "green"
    
48.                         );
    
49. 
    
50. MainLoop;
    
51. 
    
52. sub printinfo
    
53. {
    
54.          print "ok!\n";
    
55. }</p><p>
    
56. </p><p>但是下面的代码是有效的：</p><p>
    
57. </p><p>use Tk;</p><p>$mw = MainWindow->new( );
    
58. $mw->geometry("200x200");#1368
    
59. $mw->title("模式关系网");#
    
60. $mw->title("One Scrollbar/Three Listboxes");
    
61. $mw->Button(-text => "Exit",
    
62.             -command => sub { exit })->pack(-side => 'bottom');</p><p>$scltest = $mw->Scrollbar( );</p><p>$txt =  $mw->Text();</p><p># This method is called when one Listbox is scrolled with the keyboard
    
63. # It makes the Scrollbar reflect the change, and scrolls the other lists
    
64. sub scroll_Text {
    
65.   my ($scltest,   @args) = @_;
    
66.   $scltest->set(@args); # tell the Scrollbar what to display $lbs,
    
67. 
    
68. }</p><p>
    
69. $txt->configure(-yscrollcommand => [ \&scroll_Text, $scltest,
    
70.                                         ]);$txt, </p><p>
    
71. # Configure the Scrollbar to scroll each Listbox
    
72. $scltest->configure(-command => sub {
    
73.                                        $txt->yview(@_);
    
74.                                      });</p><p># Pack the Scrollbar and Listboxes
    
75. $scltest->pack(-side => 'left', -fill => 'y');
    
76. $txt->pack(-side => 'left');</p><p>$txt->insert('end', "one", "eight", "nine", "The first argument is the numberof units to scroll by.
    
77.                The value for number can be any number, but it's typically either 1 or -1. A value of
    
78.                1 means the next unit of data on the bottom or right of the widget becomes visible
    
79.                (scrolling one unit of data off the left or top). A value of -1 means that a previous
    
80.                unit of data will become visible in the top or right of the widget (one unit will scroll
    
81.                off the bottom or right of the widget). For example, every time the user clicks on the
    
82.                down arrow in a vertical Scrollbar
    
83.                associated with a Listbox, a new line shows up at the bottom of the Listbox. ",
    
84.                "This form is used when the user clicks on the slider,
    
85.                moves it around, and drops it again. The argument is a fraction, a real number from 0 to 1
    
86.                that represents the first part of the data to be shown within the widget. If the user moves
    
87.                the slider all the way to the top or left of the Scrollbar, the very first part of the data
    
88.                in the widget should be seen on the screen. This means the argument should be 0:");</p><p>
    
89. MainLoop;</p><p>
    
90. </p><p>
    
91. </p>

复制代码

hztj2005

网上找到了下面有效的例子：

1. use Tk;
   
2. use Tk::Canvas;
   
3. use Tk::Label;
   
4. 
   
5. my $mw = tkinit(-title, 'Canvas');
   
6. #$mw->geometry('250x250');
   
7. my $frame = $mw->Frame(-width, 250, -height, 250)->pack(-fill, 'both', -expand,1);
   
8. my $canvas = $frame->Scrolled('Canvas', -width, 600, -height, 600,
   
9.         -scrollbars, 'osoe'
   
10.         )->pack(-fill,'both',-expand,1);
    
11. 
    
12. my $btn = $mw->Button(-text, "Add Stuff", -command,\&addStuff)
    
13.         ->pack();
    
14. 
    
15. 
    
16. MainLoop;
    
17. 
    
18. sub addStuff{
    
19.         $canvas->createText(500, 500, -text, "Some text @ 500, 500." );
    
20.         $canvas->createRectangle(  50,  50, 110, 110, -fill, 'red');
    
21.         $canvas->createRectangle( 150, 150, 210, 210, -fill, 'green');
    
22.         $canvas->createRectangle( 250, 250, 310, 310, -fill, 'blue');
    
23.         $canvas->createText(20, 20, -text, "Some text @ 20, 20." );
    
24. #
    
25. # Your can use an array for your bounding box
    
26. # commented out to show both ways to set the scrollregion
    
27. # Just make sure you are 1 less on lower right and bottom
    
28. # Or you will have out of bounds array... easy to forget
    
29. # if you don't use a frame with your canvas
    
30. 
    
31. #$canvas->configure(-scrollregion => [ 0, 0, 599, 599]);
    
32.         $canvas->configure(-scrollregion => [$canvas->bbox('all')]);
    
33. }
    
34. 
    

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hztj2005

关键是，控件画完后加上下面语句：
$canvas->configure(-scrollregion => [$canvas->bbox('all')]);
或者下面语句指定范围
$canvas->configure(-scrollregion => [ 00, 60, 1200, 800]);