Constraints property

Esta entrada API preserva identificadores, assinaturas, blocos de código e termos PDF em sua forma original.

Defines the minimum and maximum width and height the PDF viewer is allowed to reach when its parent is resized.

Constraints exposes the four sub-properties MinWidth, MaxWidth, MinHeight and MaxHeight (all default 0 = no limit). They clamp the resize logic driven by Align, Anchors, or explicit SetBounds calls, preventing the viewer from collapsing below a usable minimum or growing beyond a sensible maximum.

For PDF reader applications the minimum dimensions matter most: rendering becomes uncomfortable below roughly 240 x 180, and the scroll bars start to fight for space with the page itself. Setting MinWidth := 320 and MinHeight := 240 avoids that visual breakdown while still letting users dock the viewer narrowly.

When a constraint kicks in, the active FitMode recalculates the page zoom against the clamped client size. This guarantees that fit-to-width and fit-to-page never produce zero or negative pixel sizes that would otherwise cause PDFium to skip rendering.

• Persistent — the four numeric sub-properties are serialised to the form file. Designed to be set in the Object Inspector or via code before the form is shown.
• Applies to both VCL and LCL. Under LCL Constraints additionally interacts with widget-set themed minimum sizes, but the PDFium control's own logic uses only the values declared here.
• Leave any sub-property at 0 to express "no limit" on that axis — for example a viewer that should never be wider than 800 px can have MaxWidth := 800 while keeping MinWidth := 0.
• Constraints take effect at the moment of every resize, so changing them at run-time may trigger an immediate OnResize and a re-fit if the current size violates the new range.

Align, Anchors, OnResize, FitMode