PtImageArea

An area for viewing an image

Class hierarchy:

PtWidget → PtBasic → PtContainer → PtImageArea

For more information, see the diagram of the widget hierarchy.

PhAB icon:

Public header:

<photon/PtImageArea.h>

Description:

PtImageArea is an area in which you can display an image. You can select an area, zoom in and out, and scroll if the image is too large to fit in the area. You can optionally display a grid when you've zoomed in past a specified amount.

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PtImageArea() can not handle alpha images.

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New resources:

Pt_ARG_IMAGEAREA_FLAGS

Flags that control the behavior of the image area:

Pt_IMAGEAREA_AUTOSCALE

Automatically scale the image to fit the size of the widget.

Pt_IMAGEAREA_ENABLE_SELECTION

Allow the user to select part of the image.

Pt_IMAGEAREA_EDITABLE_SELECTION

Allow the user to modify a selection.

Pt_ARG_IMAGEAREA_GRID_COLOR

The color of the grid, if displayed. See PgColor_t in the Photon Library Reference.

Pt_ARG_IMAGEAREA_GRID_THRESHOLD

The grid threshold, expressed as a fixed-point 16.16 number. If the zooming factor (Pt_ARG_IMAGEAREA_ZOOM) is greater than this threshold, the grid is displayed.

Pt_ARG_IMAGEAREA_IMAGE

A pointer to a PhImage_t structure (see the Photon Library Reference) that defines the image to be displayed in the image area.

Pt_ARG_IMAGEAREA_LEFT

The coordinate, in image pixels, of the left side of the image viewport. This only applies when the image is larger than the widget.

Pt_ARG_IMAGEAREA_SELECTION

A PhRect_t structure (see the Photon Library Reference) that contains the selected area of the image, in image coordinates (pixels).

Pt_ARG_IMAGEAREA_TOP

The coordinate, in image pixels, of the top side of the image viewport. This only applies when the image is larger than the widget.

Pt_ARG_IMAGEAREA_ZOOM

The zooming factor, expressed as a fixed-point 16.16 number.

Pt_CB_IMAGEAREA_DRAG

A list of PtCallback_t structures that define the callbacks invoked when the image area is dragged.

Each callback is passed a PtCallbackInfo_t structure that contains at least the following members:

reason

Pt_CB_IMAGEAREA_DRAG

reason_subtype

One of:

• Pt_IMAGEAREA_INIT
• Pt_IMAGEAREA_DRAG
• Pt_IMAGEAREA_COMPLETE

event

A pointer to a PhEvent_t structure that describes the event that caused the callback to be invoked.

cbdata

A pointer to a PtImageAreaCallback_t structure that contains at least the following members:

• PhRect_t rect — a PhRect_t structure (see the Photon Library Reference) that defines the area dragged in image coordinates (pixels).

These callbacks should return Pt_CONTINUE.

Pt_CB_IMAGEAREA_MOVEMENT

A list of PtCallback_t structures that define the callbacks that are invoked when the mouse cursor is moved over the image area.

Each callback is passed a PtCallbackInfo_t structure that contains at least the following members:

reason

Pt_CB_IMAGEAREA_MOVEMENT

reason_subtype

0 (not used).

event

A pointer to a PhEvent_t structure that describes the event that caused the callback to be invoked.

cbdata

A pointer to a PtImageAreaCallback_t structure that contains at least the following members:

• PhRect_t rect — a PhRect_t structure (see the Photon Library Reference) that defines the area the mouse moved over in image coordinates (pixels).

These callbacks should return Pt_CONTINUE.

Pt_CB_IMAGEAREA_SCROLLED

A list of PtCallback_t structures that define the callbacks that are invoked when the image area is scrolled.

Each callback is passed a PtCallbackInfo_t structure that contains at least the following members:

reason

Pt_CB_IMAGEAREA_SCROLLED

reason_subtype

The direction in which the image area scrolled:

• Pt_IMAGEAREA_SCROLLED_X
• Pt_IMAGEAREA_SCROLLED_Y

event

A pointer to a PhEvent_t structure that describes the event that caused the callback to be invoked.

cbdata

A pointer to a PtImageAreaCallback_t structure that contains at least the following members:

• PhRect_t rect — a PhRect_t structure (see the Photon Library Reference) that defines the new viewport area of the image.

These callbacks should return Pt_CONTINUE.

Pt_CB_IMAGEAREA_SELECTION

A list of PtCallback_t structures that define the callbacks invoked when the image area is selected.

Each callback is passed a PtCallbackInfo_t structure that contains at least the following members:

reason

Pt_CB_IMAGEAREA_SELECTION

reason_subtype

One of:

• Pt_IMAGEAREA_INIT
• Pt_IMAGEAREA_DRAG
• Pt_IMAGEAREA_COMPLETE

event

A pointer to a PhEvent_t structure that describes the event that caused the callback to be invoked.

cbdata

A pointer to a PtImageAreaCallback_t structure that contains at least the following members:

• PhRect_t rect — a PhRect_t structure (see the Photon Library Reference) that defines the area selected.

These callbacks should return Pt_CONTINUE.

Inherited resources:

If the widget modifies an inherited resource, the “Default override” column indicates the new value. This modification affects any subclasses of the widget.