{"id":3935,"date":"2016-06-12T16:35:31","date_gmt":"2016-06-12T08:35:31","guid":{"rendered":"http:\/\/blog.qdac.cc\/?p=3935"},"modified":"2016-06-12T16:35:31","modified_gmt":"2016-06-12T08:35:31","slug":"fmx-%e5%86%99%e4%ba%86%e4%b8%80%e4%b8%aahelper%ef%bc%8c%e4%b8%batcustomscrollbox%e7%9a%84%e5%ad%90%e7%b1%bb%e6%b7%bb%e5%8a%a0scrollinview%e6%96%b9%e6%b3%95","status":"publish","type":"post","link":"https:\/\/blog.qdac.cc\/?p=3935","title":{"rendered":"[FMX] \u5199\u4e86\u4e00\u4e2aHelper\uff0c\u4e3aTCustomScrollBox\u7684\u5b50\u7c7b\u6dfb\u52a0ScrollInView\u65b9\u6cd5"},"content":{"rendered":"<p>\u56e0\u4e3a\u8981\u7528\u5230\uff0c\u6240\u4ee5\u7279\u610f\u6dfb\u52a0\u4e86\u8fd9\u4e48\u4e2a\u65b9\u6cd5\uff0cFMX \u7684 TCustomScrollBox \u6ca1\u6709\u63d0\u4f9b\uff0c\u6216\u8005\u662f\u6211\u6ca1\u6709\u627e\u5230\u6b63\u786e\u7684\uff0c\u6240\u4ee5\u7279\u610f\u52a0\u4e86\u4e00\u4e2a\u3002\u53e6\u5916\uff0c\u9488\u5bf9 TControl \u52a0\u4e86\u4e00\u4e2a LocalToParent \u51fd\u6570\u7528\u4e8e\u5c06\u6307\u9488\u7684\u5750\u6807\u8f6c\u6362\u4e3a\u6307\u5b9a\u7ea7\u522b\u7684\u7236\u63a7\u4ef6\u7684\u5750\u6807\u3002<\/p>\n<p>\u5b8c\u6574\u6e90\u7801\u5949\u4e0a\uff0c\u4f46\u58f0\u660e\u4e0b\uff0c\u6211\u53ea\u6d4b\u8bd5\u4e86\u4e00\u90e8\u5206\u6211\u7528\u5230\u7684\u60c5\u51b5\uff0c\u5176\u5b83\u60c5\u51b5\u6ca1\u6d4b\u8bd5\uff0c\u5982\u679c\u4f60\u53d1\u73b0\u6709\u95ee\u9898\uff0c\u6b22\u8fce\u6539\u6b63\u597d\u53d1\u6211\u66f4\u65b0\u4e0b\u3002<\/p>\n<pre class=\"lang:delphi decode:true\">type\r\n   TControlHelper = class helper for TControl\r\n    function OffsetOf(AParent: TControl): TPointF;\r\n    function LocalToParent(AParent: TControl; APoint: TPointF)\r\n      : TPointF; overload;\r\n    function LocalToParent(AParent: TControl; R: TRectF): TRectF; overload;\r\n  end;\r\n\r\n  TScrollBoxHelper = class helper for TCustomScrollBox\r\n  public\r\n    procedure ScrollInView(ACtrl: TControl);\r\n  end;\r\n\r\n{ TScrollBoxHelper }\r\n\r\nprocedure TScrollBoxHelper.ScrollInView(ACtrl: TControl);\r\nvar\r\n  R, LR: TRectF;\r\n  dx, dy: Single;\r\nbegin\r\n  R := ACtrl.LocalToParent(Self, ACtrl.LocalRect);\r\n  LR := LocalRect;\r\n  if not LR.Contains(R) then\r\n  begin\r\n    if R.Left &gt; LR.Right then\r\n      dx := LR.Right-R.Right\r\n    else if R.Right &lt; R.Left then\r\n      dx := R.Left\r\n    else\r\n      dx := 0;\r\n    if R.Top &gt; LR.Bottom then\r\n      dy := LR.Bottom-R.Bottom\r\n    else if R.Bottom &lt; LR.Top then\r\n      dy := R.Top\r\n    else\r\n      dy := 0;\r\n    ScrollBy(dx, dy);\r\n  end;\r\nend;\r\n\r\n{ TControlHelper }\r\n\r\nfunction TControlHelper.LocalToParent(AParent: TControl;\r\nAPoint: TPointF): TPointF;\r\nvar\r\n  AOffset: TPointF;\r\nbegin\r\n  AOffset := OffsetOf(AParent);\r\n  Result.X := APoint.X + AOffset.X;\r\n  Result.Y := APoint.Y + AOffset.Y;\r\nend;\r\n\r\nfunction TControlHelper.LocalToParent(AParent: TControl; R: TRectF): TRectF;\r\nvar\r\n  AOffset: TPointF;\r\nbegin\r\n  AOffset := OffsetOf(AParent);\r\n  Result := R;\r\n  Result.Offset(AOffset.X, AOffset.Y);\r\nend;\r\n\r\nfunction TControlHelper.OffsetOf(AParent: TControl): TPointF;\r\nvar\r\n  ACtrl: TControl;\r\nbegin\r\n  ACtrl := Self;\r\n  Result.X := 0;\r\n  Result.Y := 0;\r\n  while (ACtrl &lt;&gt; nil) and (ACtrl &lt;&gt; AParent) do\r\n  begin\r\n    Result.X := Result.X + ACtrl.Position.X;\r\n    Result.Y := Result.Y + ACtrl.Position.Y;\r\n    ACtrl := ACtrl.ParentControl;\r\n  end;\r\n  if not Assigned(ACtrl) then\r\n    raise Exception.CreateFmt('\u6307\u5b9a\u7684\u63a7\u4ef6 %s \u4e0d\u662f %s \u7684\u5b50\u63a7\u4ef6', [Name, AParent.Name]);\r\nend;\r\n<\/pre>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u56e0\u4e3a\u8981\u7528\u5230\uff0c\u6240\u4ee5\u7279\u610f\u6dfb\u52a0\u4e86\u8fd9\u4e48\u4e2a\u65b9\u6cd5\uff0cF [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center 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