Merge pull request #37 from SnoutBug/master

Add support for Multi-touch

multitouch.go

@@ -0,0 +1,203 @@
+package uinput
+
+import (
+	"fmt"
+	"io"
+	"os"
+)
+
+// MultiTouch is an input device that uses absolute axis events.
+// Unlike the TouchPad, MultiTouch supports the simulation of multiple inputs (contacts)
+// allowing for different gestures, for exmaple pinch to zoom.
+// Each contact point is assigned a slot, making it necessary to define the maxmimum
+// expected amount of contact points .
+// Since MultiTouch uses absolute axis events, it is necessary to define the size
+// of the rectangle in which the contacs may move upon creation of the device.
+type MultiTouch interface {
+	//Gets all contacts which can then be manipulated
+	GetContacts() []multiTouchContact
+
+	// FetchSyspath will return the syspath to the device file.
+	FetchSyspath() (string, error)
+
+	io.Closer
+}
+
+type vMultiTouch struct {
+	name       []byte
+	deviceFile *os.File
+	contacts   []multiTouchContact
+}
+
+// The contact can be described as a finger contacting the surface of the MultiTouch device.
+type multiTouchContact struct {
+	multitouch  *vMultiTouch
+	slot        int32
+	tracking_id int32
+}
+
+// CreateMultiTouch will create a new multitouch device. Note that you will need to define the x and y-axis boundaries
+// (min and max) within which the contacs maybe moved around, as well as the maximum amount of contacts allowed.
+func CreateMultiTouch(path string, name []byte, minX int32, maxX int32, minY int32, maxY int32, maxContacts int32) (MultiTouch, error) {
+	err := validateDevicePath(path)
+	if err != nil {
+		return nil, err
+	}
+	err = validateUinputName(name)
+	if err != nil {
+		return nil, err
+	}
+
+	fd, err := createMultiTouch(path, name, minX, maxX, minY, maxY, maxContacts)
+	if err != nil {
+		return nil, err
+	}
+
+	var multitouch vMultiTouch = vMultiTouch{name: name, deviceFile: fd}
+
+	for i := int32(0); i < maxContacts; i++ {
+		multitouch.contacts = append(multitouch.contacts, multiTouchContact{slot: i, multitouch: &multitouch})
+	}
+
+	return multitouch, nil
+}
+
+func (vMulti vMultiTouch) GetContacts() []multiTouchContact {
+	return vMulti.contacts
+}
+
+func (vMulti vMultiTouch) FetchSyspath() (string, error) {
+	return fetchSyspath(vMulti.deviceFile)
+}
+
+func (vMulti vMultiTouch) Close() error {
+	return closeDevice(vMulti.deviceFile)
+}
+
+func createMultiTouch(path string, name []byte, minX int32, maxX int32, minY int32, maxY int32, maxContacts int32) (fd *os.File, err error) {
+	deviceFile, err := createDeviceFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("could not create absolute axis input device: %v", err)
+	}
+
+	err = registerDevice(deviceFile, uintptr(evKey))
+	if err != nil {
+		_ = deviceFile.Close()
+		return nil, fmt.Errorf("failed to register key device: %v", err)
+	}
+
+	for _, event := range []int{evBtnTouch} {
+		err = ioctl(deviceFile, uiSetKeyBit, uintptr(event))
+		if err != nil {
+			_ = deviceFile.Close()
+			return nil, fmt.Errorf("failed to register button event %v: %v", event, err)
+		}
+	}
+
+	err = registerDevice(deviceFile, uintptr(evAbs))
+	if err != nil {
+		_ = deviceFile.Close()
+		return nil, fmt.Errorf("failed to register absolute axis input device: %v", err)
+	}
+
+	for _, event := range []int{
+		absMtSlot,
+		absMtTrackingId,
+		absMtPositionX,
+		absMtPositionY,
+	} {
+		err = ioctl(deviceFile, uiSetAbsBit, uintptr(event))
+		if err != nil {
+			_ = deviceFile.Close()
+			return nil, fmt.Errorf("failed to register absolute axis event %v: %v", event, err)
+		}
+	}
+
+	var absMin [absSize]int32
+	absMin[absMtPositionX] = minX
+	absMin[absMtPositionY] = minY
+	absMin[absMtTrackingId] = 0x00
+	absMin[absMtSlot] = 0x00
+
+	var absMax [absSize]int32
+	absMax[absMtPositionX] = maxX
+	absMax[absMtPositionY] = maxY
+	absMax[absMtTrackingId] = maxContacts
+	absMax[absMtSlot] = maxContacts
+
+	return createUsbDevice(deviceFile,
+		uinputUserDev{
+			Name: toUinputName(name),
+			ID: inputID{
+				Bustype: busUsb,
+				Vendor:  0x0,
+				Product: 0x0,
+				Version: 0},
+			Absmin: absMin,
+			Absmax: absMax})
+}
+
+// The contact will be held down at the coordinates specified
+func (c multiTouchContact) TouchDownAt(x int32, y int32) error {
+	var events []inputEvent
+
+	events = append(events, inputEvent{
+		Type:  evAbs,
+		Code:  absMtPositionX,
+		Value: x,
+	})
+
+	if x == 0 && y == 0 {
+		y--
+	}
+
+	events = append(events, inputEvent{
+		Type:  evAbs,
+		Code:  absMtPositionY,
+		Value: y,
+	})
+
+	c.tracking_id = c.slot
+
+	return c.sendAbsEvent(events)
+}
+
+// The contact will be raised off of the surface
+func (c multiTouchContact) TouchUp() error {
+	c.tracking_id = -1
+	return c.sendAbsEvent(nil)
+}
+
+func (c multiTouchContact) sendAbsEvent(events []inputEvent) error {
+	var ev []inputEvent
+
+	ev = append(ev, inputEvent{
+		Type:  evAbs,
+		Code:  absMtSlot,
+		Value: c.slot,
+	})
+
+	ev = append(ev, inputEvent{
+		Type:  evAbs,
+		Code:  absMtTrackingId,
+		Value: c.tracking_id,
+	})
+
+	if events != nil {
+		ev = append(ev, events...)
+	}
+
+	for _, iev := range ev {
+		buf, err := inputEventToBuffer(iev)
+		if err != nil {
+			return fmt.Errorf("writing abs event failed: %v", err)
+		}
+
+		_, err = c.multitouch.deviceFile.Write(buf)
+		if err != nil {
+			return fmt.Errorf("failed to write abs event to device file: %v", err)
+		}
+	}
+
+	return syncEvents(c.multitouch.deviceFile)
+}