HScrollBar value glitch

[Cyclone]

Hi,

I created a HScrollBar control and set its maxvalue to 255.
Changing its value will show the value in a NumericUpDown control.

When I scroll to its maximum it only reaches 446... Shouldn't it reach 255?
To fix this I have to add 0x9 to the max value of the HSCrollBar.

// NumericUpDow1
			this->NumericUpDow1->Name = L"label1fda";
			this->NumericUpDow1->Location = System::Drawing::Point(150, 125);
			this->NumericUpDow1->Text = "Current Value";
			this->NumericUpDow1->Size = System::Drawing::Size(190,25);
			this->NumericUpDow1->ValueChanged += gcnew System::EventHandler(this, &Music_FormB::NumericUpDow1_Val_Changed);
			this->NumericUpDow1->Maximum = 255;

// Music Speed scroll
			this->Music_Scroll->AutoSize = true;
			this->Music_Scroll->Location = System::Drawing::Point(80, 75);
			this->Music_Scroll->Name = L"label1fda";
			this->Music_Scroll->Size = System::Drawing::Size(325, 30);
			this->Music_Scroll->TabIndex = 0;
			this->Music_Scroll->ValueChanged += gcnew System::EventHandler(this, &Music_FormB::Music_Scroll_Val_Changed);
			this->Music_Scroll->Maximum = 0xFF + 0X9;

private: System::Void Music_Scroll_Val_Changed(System::Object^ sender, System::EventArgs^ e)
	{
		NumericUpDow1->Value = Music_Scroll->Value;
	}

[Peter87]

I did some searching and what I found suggests you might want to set the "LargeChange" value to 1 or compensate for it somehow...

https://stackoverflow.com/questions/2882789/net-vertical-scrollbar-not-respecting-maximum-property

https://social.msdn.microsoft.com/Forums/windows/en-US/98d5499c-ea33-44c8-9920-ce8a2116cb15/scrollbarvalue-cant-be-set-to-scrollbarmaximum?forum=winforms

[Peter87]

Are you sure a ScrollBar is the most suitable control for what you're doing? Have you considered using a TrackBar instead?

[Cyclone]

Thanks Peter.

If you don't want the scrollbar to compensate for viewable space, you have to set your LargeChange to 1.

This solved my issue. What does it mean? I just don't understand why I need to change the "LargeChange" Value???

[Peter87]

Scrollbars are normally used when you want to display something in a space that is too small to show all at once. For example, this web page is probably too long to display all at once so your browser shows a vertical scrollbar to the right to let you choose which part of the page you want to view at the moment.


If "Maximum" is the y position at the bottom of the page (i.e. the height - 1), ...

... "Value" is the topmost y position of the page that is currently within the visible area, ...

... and "LargeChange" is the height of the visible area ...

... then it makes sense that you cannot scroll down so that Value becomes equal to the Maximum ...

... unless the visible area is only 1 pixel high or your browser allows you to scroll past the end of the page (so that the bottom gets all the way to the top).


I haven't had the opportunity to test and the official documentation doesn't seem to explain it like this but it is how I understand the discussions I linked to.

[Cyclone]

Thanks for the explanation. Hmm that makes sense.