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MouseAction


Unit:SDL_polchart
Class:TPolChart
Declaration:property MouseAction: TMouseActMode;

The property MouseAction facilitates interactive zooming and panning of the data. This property may take the following possible values.

maDragCrossH Drag any visible crosshair using the mouse. If more than one crosshair is visible, the crosshair closest to the mouse cursor when clicking the left mouse button is selected. The OnCrossHairMove event is triggered whenever a crosshair is moved by the mouse.
maDragLabel Drag any visible user-defined text label. The text label closest to the mouse cursor when pressing the left mouse button can be moved interactively when holding down the left mouse button. The OnTextLabelMove event is triggered whenever a crosshair is moved by the mouse.
maNone No built-in interaction is possible. The only way to apply a mouse controlled action is by utilizing the mouse events.
maPan The data display can be panned by pressing and holding the left mouse button. The data image will then follow the mouse movement.
maPanHoriz The data display can be panned only horizontally by pressing and holding the left mouse button.
maPanVert The data display can be panned only vertically by pressing and holding the left mouse button.
maZoomDrag This mode enables the user both to increase and to decrease the magnification factor of the graph. The left mouse button has to be pressed and held down. The magnification of the data image will then follow the mouse movement. Moving to the bottom zooms out of the data; moving to the top zooms into the data.
maZoomWind,
maZoomWindPos
The user can zoom into a rectangular region of the data display. Therefore she has to press and hold down the left mouse button at one of the corners of the intended region. Then a rectangle follows the mouse cursor indicating the region to be zoomed. Releasing the left button selects this region and zooms into the data by displaying the selected region. Note, that TPolChart does not distinguish between maZoomWind and maZoomWindPos.

Hint 1: These interactive modes will function smoothly only on a powerful computer with a proper graphics card.

Hint 2: In the case of type ambiguities concerning maNone please visit the SDL TechnNotes.

Example: This property is used in the following example program (see http://www.lohninger.com/examples.html for downloading the code): poldiag


Last Update: 2016-Feb-23