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High DPI Inheritance of Form #606

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PetrDaricek opened this issue Feb 16, 2016 · 1 comment
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High DPI Inheritance of Form #606

PetrDaricek opened this issue Feb 16, 2016 · 1 comment
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@joachimmarder
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Bug Pull Requests Invited There are no current plans to address the issue, but we would be happy if someone supplies a PR.

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@PetrDaricek
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Hello,
I created FormAncestor and place on it VirtualTree component. Second I Created FormChild, it is inherited from FormAncestor. I Modified some properties of VirtualTree (I don't know if this step is required). All I develop on Windows 7 with standard 96DPI.
When I run this program on Windows 8.1. with 192 DPI (200%) header and rows are to big. I searched why and I recognize this algorithms:

  1. When loading FormAncestor DFM, then from TCustomForm.ReadState(Reader: TReader) method is called ScaleControls - > VirtualTree.ChangeScale -> VirtualHeader.ChangeScale. Height of Header has been changed too 19(Default) * 2 (192/96 DPI).
  2. When loading FormChild DFM, then from TCustomForm.ReadState(Reader: TReader) method is called ScaleControls - > VirtualTree.ChangeScale -> VirtualHeader.ChangeScale again. Heigh of Header has been changed too** 38 * 2 (192/96 DPI).**

So Header is more bigger than should be.
I see in VCL units are flags to Rescale and rescale is performed only when this flag is set. For example, when I Load from dfm with of TButton, than in SetWidth method is set rescale flag to witdh. In TButton.ChangeScale is change with only if this flag is set, and on end of changescale is Flags unset.
This mechanism ensures that the calling of Cahgnscale on with is only once.

I think it is bug in Virtual Tree.
I tested it on Delphi 10 Seatle with Subscription Update 1, Windows 7 64b (96DPI), and Windows 8.1 64b (192 DPI).
@joachimmarder joachimmarder added Bug Pull Requests Invited There are no current plans to address the issue, but we would be happy if someone supplies a PR. labels Feb 16, 2016
@joachimmarder
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I agree, this sounds like a bug.

joachimmarder pushed a commit that referenced this issue Feb 28, 2016
Fixed issue #606: High DPI Inheritance of Form
68e82be 
* TBaseVirtualTree.ChangeScale() now respects inherited property ScalingFlags
* Improved code order in TVTHeader.ChangeScale() to prevent duplicate scaling
@joachimmarder joachimmarder self-assigned this Feb 28, 2016
ValtsS pushed a commit to ValtsS/Virtual-TreeView that referenced this issue Jan 25, 2019
@ValtsS
Fixed issue JAM-Software#606: High DPI Inheritance of Form
9ab1df7 
* TBaseVirtualTree.ChangeScale() now respects inherited property ScalingFlags
* Improved code order in TVTHeader.ChangeScale() to prevent duplicate scaling
# Conflicts:
#	Source/VirtualTrees.pas
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