mod: reduce the amount of unnecessary re-renderings

src/widget/List.zig

@@ -64,18 +64,32 @@ pub fn Widget(comptime Event: type, comptime Renderer: type) type {
                     var require_render = true;
                     if (key.matches(.{ .cp = 'g' })) {
                         // top
-                        this.idx = 0;
+                        if (this.idx != 0) {
+                            this.idx = 0;
+                        } else {
+                            require_render = false;
+                        }
                     } else if (key.matches(.{ .cp = 'G' })) {
                         // bottom
-                        this.idx = this.contents.items.len -| 1;
+                        if (this.idx < this.contents.items.len -| 1) {
+                            this.idx = this.contents.items.len -| 1;
+                        } else {
+                            require_render = false;
+                        }
                     } else if (key.matches(.{ .cp = 'j' })) {
                         // down
                         if (this.idx < this.contents.items.len -| 1) {
-                            this.idx +|= 1;
+                            this.idx += 1;
+                        } else {
+                            require_render = false;
                         }
                     } else if (key.matches(.{ .cp = 'k' })) {
                         // up
-                        this.idx -|= 1;
+                        if (this.idx > 0) {
+                            this.idx -= 1;
+                        } else {
+                            require_render = false;
+                        }
                     } else {
                         require_render = false;
                     }

src/widget/RawText.zig

@@ -55,18 +55,32 @@ pub fn Widget(comptime Event: type, comptime Renderer: type) type {
                 .key => |key| {
                     if (key.matches(.{ .cp = 'g' })) {
                         // top
-                        this.line = 0;
+                        if (this.line != 0) {
+                            this.line = 0;
+                        } else {
+                            require_render = false;
+                        }
                     } else if (key.matches(.{ .cp = 'G' })) {
                         // bottom
-                        this.line = this.line_index.items.len -| 1 -| this.size.rows;
+                        if (this.line < this.line_index.items.len -| 1 -| this.size.rows) {
+                            this.line = this.line_index.items.len -| 1 -| this.size.rows;
+                        } else {
+                            require_render = false;
+                        }
                     } else if (key.matches(.{ .cp = 'j' })) {
                         // down
                         if (this.line < this.line_index.items.len -| 1 -| this.size.rows) {
-                            this.line +|= 1;
+                            this.line += 1;
+                        } else {
+                            require_render = false;
                         }
                     } else if (key.matches(.{ .cp = 'k' })) {
                         // up
-                        this.line -|= 1;
+                        if (this.line > 0) {
+                            this.line -= 1;
+                        } else {
+                            require_render = false;
+                        }
                     } else {
                         require_render = false;
                     }