3.3. Navigation In Time

In addition to the menu entries and keystrokes mentioned in Section 3.1.3, there are two more ways to move in time in the Intel Trace Analyzer. One is by using the scroll bar found below the timelines and another is by using the mouse to zoom into a time interval. Similar to the keystrokes, these operations manipulate the zoom stack. Refer to Section 3.3.1 for a detailed explanation.

To move the View by a quarter of a screen to a selected direction, click on the arrow buttons of the scroll bar. To move the View by one entire screen, click into the bar. Both actions push the new interval onto the zoom stack.

To use the mouse for zooming, left-click into the timeline (even clicking into the Timescale works) and select the region of the new time interval, keeping the left mouse button pressed. On releasing the left mouse button this new interval is pushed onto the zoom stack.

Figure 3-7. Zooming with the mouse

3.3.1. The Zoom Stack

The zoom stack supports navigation in time by storing previously displayed time intervals. These time intervals are restored when required. Navigation using the keyboard or mouse is quite intuitive without detailed knowledge of the zoom stack. Nevertheless, an explanation is given below for the sake of complete reference.

Consider a trace file spanning the time from 0 to 100 seconds. When the first View is opened the zoom stack looks like this:

Figure 3-8. The zoom stack

0:(0;100)(50;100)
Each stack entry has the syntax (Start; Stop)(Center; Width). Zooming in using I (Zoom In), magnifies the Chart by a factor of 2 around the current center.In the above example, the center is at 50 seconds. Therefore, zooming in twice using I will result in a stack as shown in Figure 3-9.

Figure 3-9. State of the zoom stack - Zoomed in twice


3:(55;65)(60;10)
2:(50;70)(60;20)
1:(40;80)(60;40)
0:(0;100)(50;100)

Figure 3-9 shows that a stack level is created for each action performed. On pressing Ctrl+Right twice, the time frame of the Chart is moved to the right by two window sizes. Using the state shown in Figure 3-10, the differences between Back (B), Zoom Out (O) and Zoom Up (U) are explained below.

Figure 3-10. State of the zoom stack - Moved two window sizes to the right


5:(75;85)(80;10)
4:(65;75)(70;10)
3:(55;65)(60;10)
2:(50;70)(60;20)
1:(40;80)(60;40)
0:(0;100)(50;100)

Back (B): Pressing B in the state shown in Figure 3-10 pops out one level of the stack and the previous time frame is displayed as shown in Figure 3-11.

Figure 3-11. State of the zoom stack - after Back (B)


4:(65;75)(70;10)
3:(55;65)(60;10)
2:(50;70)(60;20)
1:(40;80)(60;40)
0:(0;100)(50;100)

Zoom Out: Using O in Figure 3-10 lowers the magnification (doubles the width) and pushes a new item on the stack. Zooming out using O in the state shown in Figure 3-10 results in the stack as shown below.

Figure 3-12. State of the zoom stack - after Zoom Out (O)


6:(70;90)(80;20)
5:(75;85)(80;10)
4:(65;75)(70;10)
3:(55;65)(60;10)
2:(50;70)(60;20)
1:(40;80)(60;40)
0:(0;100)(50;100)

Zoom Up (U): The resultant zoom after using U is a little more complicated. Pressing U keeps the current center and uses the magnification from before the latest "zoom in" (which is the change from level 2 to 3 in Figure 3-10) and to clear the stack up to and including the last "zoom in" found. In our example the current center is 80 and the width from stack level 2, which is 20, is used.

Figure 3-13. State of the zoom stack - after Zoom Up (U)


2:(70;90)(80;20)
1:(40;80)(60;40)
0:(0;100)(50;100)

Reset (R) : Reset clears the stack and pushes one entry covering the full time range of the trace file. Therefore, on pressing R, the stack shown in Figure 3-8 is reestablished.