Re: [PATCH 2/2] Truncate caret of text input field at top & bottom boundaries.

I was wondering why there is one pixel gap at the cropped caret, so that is the reason. 

I can't thank you enough for describing me this so well,

As you said, caret should be cropped against crop rectangle but it is not happening, so I will try to find out why is that.

Regards

Achal

On Fri, Mar 21, 2014 at 4:21 AM, Michael Drake <mike@smoothartist.com> wrote:

Hi Achal-Aggarwal,

Thanks for looking at this.

On 20/03/14 21:21, Achal-Aggarwal wrote:

---
  desktop/textarea.c | 9 ++++++++-
  1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/desktop/textarea.c b/desktop/textarea.c
index 8e4b1dd..c148a58 100644
--- a/desktop/textarea.c
+++ b/desktop/textarea.c
@@ -462,12 +462,19 @@ static bool textarea_set_caret_internal(struct textarea *ta, int caret_b)
                                                ((ta->bar_x == NULL) ?
                                                0 : SCROLLBAR_WIDTH)
                        };
+
+                       /* Truncate height of caret on top and bottom boundaries */
+                       height = ta->line_height;
+                       if (y - ta->scroll_y + height > cr.y1) {
+                               height = cr.y1 - y + ta->scroll_y;
+                       }
+

OK, so you're fixing this by adjusting the height of the caret in the core.  This is not the right approach.  The way the caret gets rendered is the core asks the front end to render a caret, and there's nothing that says the front end's caret looks the same all the way up.

So for example, if the caret is this shape:

- - - - - - - - - - -
  \ /
   |
   |
   |
- -|- - - - - - - - -
   |
   |
  / \


Then by adjusting the height you ask the front end to render this:

- - - - - - - - - - -
  \ /
   |
   |
  / \
- - - - - - - - - - -

When what you should be doing is letting the front end crop the caret to the area:

- - - - - - - - - - -
  \ /
   |
   |
   |
- - - - - - - - - - -

                        msg.ta = ta;
                        msg.type = TEXTAREA_MSG_CARET_UPDATE;
                        msg.data.caret.type = TEXTAREA_CARET_SET_POS;
                        msg.data.caret.pos.x = x - ta->scroll_x;
                        msg.data.caret.pos.y = y - ta->scroll_y;
-                       msg.data.caret.pos.height = ta->line_height;
+                       msg.data.caret.pos.height = height;
                        msg.data.caret.pos.clip = &cr;

The clip rectangle gets passed to the front end here.  So in the front end caret rendering code, it should be applying the clip rectangle it gets given.

It's probably just ignoring the clip rectangle at the moment.

Cheers,

Michael

--
Achal