Mouse events
We already had the opportunity to make sure that we receive mouse events using the indicator EventAll.mq5 from the section Event-related chart properties. The CHARTEVENT_CLICK event is sent to the MQL program on each click of the mouse button in the window, and the CHARTEVENT_MOUSE_MOVE cursor movement and CHARTEVENT_MOUSE_WHEEL wheel scroll events require prior activation in the chart settings, for which the CHART_EVENT_MOUSE_MOVE and CHART_EVENT_MOUSE_WHEEL properties serve, respectively (both are disabled by default).
If there is a graphic object under the mouse, when the button is pressed, not only the CHARTEVENT_CLICK event is generated but also CHARTEVENT_OBJECT_CLICK.
For the CHARTEVENT_CLICK and CHARTEVENT_MOUSE_MOVE events, the parameters of the OnChartEvent handler contain the following information:
- lparam - X coordinate
- dparam - Y coordinate
In addition, for the CHARTEVENT_MOUSE_MOVE event, the sparam parameter contains a string representation of a bitmask describing the status of mouse buttons and control keys (Ctrl, Shift). Setting a particular bit to 1 means pressing the corresponding button or key.
Bits |
Description |
|---|---|
0 |
Left mouse button state |
1 |
Right mouse button state |
2 |
SHIFT key state |
3 |
CTRL key state |
4 |
Middle mouse button state |
5 |
State of the first additional mouse button |
6 |
State of the second additional mouse button |
For example, if the 0th bit is set, it will give the number 1 (1 << 0), and if the 4th bit is set, it will give the number 16 (1 << 4). Simultaneous pressing of buttons or keys is indicated by a superposition of bits.
For the CHARTEVENT_MOUSE_WHEEL event, the X and Y coordinates, as well as the status flags of the mouse buttons and control keys, are encoded in a special way inside the lparam parameter, and the dparam parameter reports the direction (plus/minus) and amount of wheel scrolling (multiples of ±120).
8-byte integer lparam combines several of the mentioned information fields.
Bytes |
Description |
|---|---|
0 |
Value of short type with the X coordinate |
1 |
|
2 |
Value of short type with the Y coordinate |
3 |
|
4 |
Bitmask of button and key states |
5 |
Not used |
6 |
|
7 |
Regardless of the type of event, mouse coordinates are transmitted relative to the entire window, including subwindows, so they should be recalculated for a specific subwindow if necessary.
For a better understanding of CHARTEVENT_MOUSE_WHEEL, use the indicator EventMouseWheel.mq5. It receives and decodes the messages, and then outputs their description to the log.
#define KEY_FLAG_NUMBER 7
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Run the indicator on the chart and scroll the mouse wheel by pressing various buttons and keys in turn. Here is an example result:
X=186 Y=303 D=-120
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