<KeyPosition>

Specifies a view's position at a specific moment during the motion sequence. This attribute is used to adjust the default path of the motion.

For example, if an object begins at the upper-left corner and ends at the lower-right corner, the default motion sequence moves the object diagonally down the screen. By adding one or more <KeyPosition> elements, you can deform the path.

Syntax

<KeyPosition
    motion:motionTarget="@id/targetPath"
    motion:framePosition="percentage"
    motion:keyPositionType="type"
    motion:percentX="xOffset"
  motion:percentY="yOffset"
/>

Attributes

motion:motionTarget
View whose motion is controlled by this <KeyPosition>.
motion:framePosition
Integer from 1 to 99 specifying when in the motion sequence the view reaches the point specified by this <KeyPosition>. For example, if framePosition is 25, the view reaches the specified point one-quarter of the way through the motion.
motion:percentX, motion:percentY
Specify the position the view reaches. The keyPositionType attribute specifies how these values are interpreted.
motion:keyPositionType
Specifies how the percentX and percentY values are interpreted. Possible settings are the following:
  • parentRelative

    • percentX and percentY are specified relative to the parent view. X is the horizontal axis, ranging from 0 for the left side to 1 for the right side. Y is the vertical axis, with 0 being the top and 1 being the bottom.

    For example, if you want the target view to reach a point midway down the right side of the parent view, set percentX to 1 and percentY to 0.5.

  • deltaRelative

    • percentX and percentY are specified relative to the distance the view moves over the course of the whole motion sequence. X is the horizontal axis and Y is the vertical axis. In both cases, 0 is the starting position of the view in that axis, and 1 is the final position.

    Suppose the target view moves 100 dp up and 100 dp to the right, but you want the view to move down 40 dp for the first quarter of the motion, then arc back up. Set framePosition to 25, keyPositionType to deltaRelative, and percentY to -0.4.

  • pathRelative

    • The X-axis is the direction the target view moves over the course of the path, with 0 being the starting position and 1 being the final position. The Y-axis is perpendicular to the X-axis, with positive values to the left of the path and negative values to the right. So the initial position of the view is (0,0) and the final position is (1,0). Setting a non-zero percentY causes the view to arc to one direction or the other.

    Suppose you want the view to take half of the motion sequence to cover 10% of the total distance, then speed up to cover the other 90%. Set framePosition to 50, keyPositionType to pathRelative, and percentX to 0.1. percentY remains 0.

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