gitk: TIP 474 based mouse wheel support

TIP 474 provides uniform way to handle mouse wheel events for all
platforms.

> TIP 474: Treat the mouse wheel events in a uniform way
> https://core.tcl-lang.org/tips/doc/trunk/tip/474.md

TIP 474 was available since Tk 8.7 for development version,
and also available since Tk 9.0 for release version.

So, use TIP 474 based mouse wheel event handler for all Tk 9 based
platforms.

Also, adjust horizontal scroll size from 5 to 1 for human eyes.
5 is too big to follow eyes while scrolling.

Signed-off-by: YOKOTA Hiroshi <[email protected]>

Author: qykth-git

gitk

@@ -2671,27 +2671,42 @@ proc makewindow {} {
     pack .ctop -fill both -expand 1
     bindall <1> {selcanvline %W %x %y}
     #bindall <B1-Motion> {selcanvline %W %x %y}
-    if {[tk windowingsystem] == "win32"} {
-        bind . <MouseWheel> { windows_mousewheel_redirector %W %X %Y %D }
-        bind $ctext <MouseWheel> { windows_mousewheel_redirector %W %X %Y %D ; break }
+    global have_tk90
+    if {$have_tk90} {
+        bindall <MouseWheel> {
+            set delta [expr {((%D) >= 0) ? -5 : 5}]
+            allcanvs yview scroll $delta units
+        }
+        bindall <Shift-MouseWheel> {
+            set delta [expr {((%D) >= 0) ? -1 : 1}]
+            $canv xview scroll $delta units
+        }
     } else {
-        bindall <ButtonRelease-4> "allcanvs yview scroll -5 units"
-        bindall <ButtonRelease-5> "allcanvs yview scroll 5 units"
-        bind $ctext <Button> {
-            if {"%b" eq 6} {
-                $ctext xview scroll -5 units
-            } elseif {"%b" eq 7} {
-                $ctext xview scroll 5 units
-            }
-        }
-        if {[tk windowingsystem] eq "aqua"} {
-            bindall <MouseWheel> {
-                set delta [expr {- (%D)}]
-                allcanvs yview scroll $delta units
-            }
-            bindall <Shift-MouseWheel> {
-                set delta [expr {- (%D)}]
-                $canv xview scroll $delta units
+        switch -- [tk windowingsystem] {
+            "win32" {
+                bind .      <MouseWheel> { windows_mousewheel_redirector %W %X %Y %D }
+                bind $ctext <MouseWheel> { windows_mousewheel_redirector %W %X %Y %D }
+            }
+            "aqua" {
+                bindall <MouseWheel> {
+                    set delta [expr {- (%D)}]
+                    allcanvs yview scroll $delta units
+                }
+                bindall <Shift-MouseWheel> {
+                    set delta [expr {- (%D)}]
+                    $canv xview scroll $delta units
+                }
+            }
+            "x11" {
+                bindall <ButtonRelease-4> "allcanvs yview scroll -5 units"
+                bindall <ButtonRelease-5> "allcanvs yview scroll  5 units"
+                bind $ctext <Button> {
+                    if {"%b" eq 6} {
+                        $ctext xview scroll -1 units
+                    } elseif {"%b" eq 7} {
+                        $ctext xview scroll  1 units
+                    }
+                }
             }
         }
     }