ZacharyZhang-NYandClaude Opus 5.5
bcce34cda1
MyGo v0.5.5 returns ui.Element as a checked value handle instead of a
pointer. Migrated with `mygo migrate-ui`, then fixed what the codemod
leaves to review:
- Element nil checks become .Valid(); absent elements are ui.Element{}.
- Input handlers and paint callbacks run outside the build pass, where
elements expire and Context methods are inert: read IsDisabled into a
local during the build, keep a ui.Handle for Focus, use c.Services()
for clipboard access, create ui.Local state during the build.
- Add core.AutoFocus: v0.5.5 records an overlay's opener after its
content builds, so same-frame autofocus lost focus restore on close.
It focuses one frame later; cascader rows defer their focus likewise.
- core.OverlayLayer identifies build passes by the root element, not
c.Now(), which repeats across passes and under the Tester clock.
- Context menus survive the opening press counted as PressedOutside;
split button tooltip no longer reorders its open menu; disabled
menubar rows pass presses to the panel; Form defers blur-started
async checks so the growing message no longer moves Submit away
from the release; Combobox drops its disabled copy now that MyGo
blocks typing under a disabled wrapper (canary flipped to a guard).
- The Tester clock is virtual: tests use Advance/Now instead of
time.Sleep/time.Now and read element state inside the view. The web
mirror advances the clock to wall time before each frame and input.
- AGENTS.md and docs describe the value Element API and the new pin.
Snapshot goldens are darwin-only and were not re-verified here.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
50 lines
2.0 KiB
Markdown
50 lines
2.0 KiB
Markdown
# 007 ScrollArea 滚动区域
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## 用途
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纵向、横向或双向滚动内容。支持滚轮、触控板、滚动条拖动与键盘；可读取、设置并保留滚动位置。基于 MyGo `ui.Scroll`。
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## 最小示例
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```go
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var offset ui.ScrollState
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layout.ScrollArea(c, &offset, layout.ScrollAreaOptions{Label: "Log"}, func() {
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for range 50 {
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ui.Text(c, "A line of the log")
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}
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}).Height(200)
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```
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签名：`func ScrollArea(c *ui.Context, state *ui.ScrollState, opts ScrollAreaOptions, children func()) ui.Element`
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## 参数
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| 字段 | 类型 | 默认值 | 含义 |
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| --- | --- | --- | --- |
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| `state` | `*ui.ScrollState` | nil | 滚动位置。设置 `X`/`Y` 即滚动到该处，`math.MaxFloat32` 表示末尾；组件写回 `MaxX`/`MaxY`。nil 时按区域在视图中的位置保留。 |
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| `Direction` | `ScrollDirection` | `ScrollVertical` | `ScrollVertical`、`ScrollHorizontal`、`ScrollBoth`；非法值 panic。 |
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| `Label` | `string` | "" | 区域的无障碍名称。 |
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| `children` | `func()` | 必填 | 内容；nil 时 panic。 |
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需给区域尺寸（`Height`、`Grow` 等）。
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## 状态
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- 内容溢出时区域可获得焦点，键盘焦点环画在区域内侧：先留 2 DIP 间隔，再画 2 DIP Focus 色环线，避免被父级裁剪。溢出状态在布局后变化时组件立即重建，焦点停靠随之更新。
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- 不溢出时不进入 Tab 序列。
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- 滚动条为 MyGo 叠加式滑块，颜色取主题 Scrollbar（TextMuted 50%），指针悬停时显示，不占布局空间。
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- 切换主题、折叠周围布局都不重置位置。
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## 事件
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无独立事件；比较 `state.X`/`state.Y` 的变化即可得知滚动。
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## 键盘操作
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焦点在区域或其内容上时：方向键滚动 40 DIP，Page Up/Down 与 Space/Shift+Space 翻页，Home/End 到顶部/底部（macOS 另有 Cmd+↑/↓）。文本输入等自行处理这些键的控件优先。
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## 限制
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- 滚动条只在悬停时显示，不提供常驻滚动条（MyGo 滚动条不占空间的设计）。
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- 大量行请使用虚拟化列表，ScrollArea 会构建全部子项。
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